The critical turning point in the history of the Roman Empire came during the reign of Marcus Aurelius when a combination of problems led to the collapse of the Pax Romana, after which the Empire, particularly in the west, entered a long period of decline.
Marcus Aurelius (161-180):  one of Rome's finest emperors and one of the most important philosophers in the ancient world.  (His little book, The Meditations, written during his campaigns, is a major statement of Stoic philosophy.)  Ironically, the crisis which led to the collapse of the Pax Romana came during the reign of a 'good emperor.'
'German Problem':  the rising pressure of the Germans on the northern borders of the Roman Empire.  After centuries of relative quiet, the Germans began once again to go into motion.  During the reign of Marcus Aurelius, they began to exert intense pressure on Rome's northern frontier.
Germans:  Indo-European speaking people who lived north of the Roman Empire, in the heavily forested region of north-central Europe.
Indo-European Languages:  A family of languages, all of which appear to be descended from a single parent language or mother tongue, originally spoken by people living on the vast grasslands of southern Russia, near the Caspian Sea.  Most modern European languages are part of the Indo-European language family (the only exceptions being Basque, Finnish, and Hungarian).  The list includes:  Greek, Latin, the Latin-based Romance languages, as well as all Germanic, Celtic, and Slavic languages.
Compare to Semitic Languages:  A family of languages, all of which appear to be descended from a single parent which originated in the Arabian desert south of the Fertile Crescent.  Starting even earlier than the Indo-Europeans, semitic speakers began to push out of their homeland and, as they did so, their speech developed into a number of different, though closely-related languages.  The major semitic languages surviving into the modern world are Arabic and Hebrew.
Indo-European (sometimes called Indo-Aryan or simply Aryan):  a person who speaks an Indo-European language.  (In this sense, English speakers are Indo-Europeans.)
Indo-European Migration:  Around 2500 B. C., probably as a result of population pressures, the Indo-Europeans began to push out in all directions, in a movement known as the Indo-European Migration, the largest folk migration in history.  Centuries before the birth of Jesus, they had already come to inhabit much of the region between India and Britain.  As these such people move apart, the original language fragmented into dialects, which in turn, became independent languages (a common process in the evolution of languages).  Among the major Indo-European groups were the Sanscrit speaking peoples of India, the Persians, Hittites (Asia Minor), Greeks, Italic Tribes (including the Romans), Celts, Germans, and Slavs.  Note:  the Indo-European migration had its greatest impact on the European continent.  Here, Indo-European invaders subdued or displaced almost all of the earlier inhabitants; consequently, almost all Europeans and their descendants speak Indo-European languages.
Relation of Indo-European and Romance Languages:  the Romance Languages (Italian, French, Spanish, Portuguese, Rumanian) all evolved from Latin, the language of the Romans.  (Hence their name which means "Roman-like.")  Since Latin is an Indo-European Language, all the languages which grew out of it must also be Indo-European.  Therefore, it is correct to say that "all Romance languages are Indo-European languages."  However, the opposite is not true:  you cannot say that "all Indo-European languages are Romance languages."  Greek, Hittite, Persian, Sanscrit, even Latin are all Indo-European, but are not Romance Languages.
Three Indo-European groups - the Celts, Germans, and Slavs - pushed into northern and central Europe and, over the centuries, jostled one another for position.  Apparently, it was pressure from the Germans which pushed the Celts into Gaul and Britain where the Romans found them in the first century B. C. and, during the next two centuries, conquered most of them.  After the conquest, most Celts gave up their languages and adopted Latin.  Celtic languages (Gaelic, Welsh, and Breton) survive in areas which not thoroughly Romanized or maintained their independence.
Domino Effect:  when human populations migrate, one group may be set in motion at least in part because it is being pushed by the group behind it.  This is what historians call the domino effect.  Example:  when the Germans pushed into central Europe around 500 B. C. and drove the Celts westward into Gaul and Britain.
Factors which set a people like the Germans in motion:
(1)  the lure of better land or a warmer climate
(2)  an exploding population
(3)  a food crisis brought on by population increase
(4)  simple love of adventure
The Germans were divided into two principal 'waves':
(1)  Teutons (including the Angles, Saxons, Franks) who inhabited the northwestern frontier of the Roman Empire
(2)  Goths (including Visigoths, Ostrogoths, and Vandals) who inhabited the northeastern frontier of the Roman Empire
The Romans first encountered the Germans in 113 B. C. when a mixed horde of Celts and Germans raided northern Italy.  On that occasion, they were annihilated by a Roman army.  For nearly five centuries, the Romans would continue to defeat the Germans on most occasions when they met in battle.  Then, around 400 A. D., this pattern was reversed as the Germans got the upper hand and overran the western provinces of the Roman Empire.
As long as the Celts possessed the territory between the Romans and Germans, they served as a buffer.  However, around 50 B. C., Julius Caesar conquered Gaul, and established Rome's border along the Rhine River.  As a result, the Romans and Germans came to share a frontier with the Germans hundreds of miles in length.
Rhine-Danube Line:  the name given the northern border of the Roman Empire, which ran along the Rhine and Danube Rivers, from the English channel to the Black Sea.  On one side of this line were the Germans; on the other, the Romans.
Under the Empire, the Romans adopted what was largely a defensive posture toward dangerous neighbors like the Germans.  The first emperor, Augustus, established a new military policy for Rome:  to defend existing borders from attack, rather than to continue expanding those borders, as Rome had done in the past.  With a few exceptions, the emperors from Augustus onward followed this defensive strategy.  One of these few exceptions came late in the reign of Augustus, when the emperor violated his own defensive strategy by mounting an ill-fated invasion of Germany in 9 A. D.  The overconfident Roman general blundered into a German ambush in the Teutoberg Forests where his legions were wiped out.  As a result, the Roman attempt to add Germany to the empire ended.
Arminius Hermann:  the German leader at Teutoberg Forest who defeated the Romans and thereby became the first major figure in German history.
Battle of Teutoberg Forest (9 A. D):  battle at which a Roman army blundered into disastrous ambush from which very few Romans escaped.  This and the much later Roman defeat at the battle of Adrianople (378 A. D.), both of which were fought against the Germans, rank among Rome's greatest military disasters.
Source Problem:  In learning about early German history, historians face a common problem.  The Germans, like most pastoral nomads were pre-literate.  Not until several centuries after they first came in contact with the higher civilization of Rome did the Germans finally borrow writing from the Romans.  As a result, our principal knowledge concerning early German society comes not from the Germans themselves, but from the Roman authors who wrote about them, men such as:
(1)  Julius Caesar (1st century B. C.)
(2)  Tacitus (1st century A. D.)
(3)  Ammianus Marcellinus (4th century A. D.)
German Society:
German males delighted in warring, wenching, drinking, feasting, and hunting; while leaving most of the work to the young, the old, and the women.
War was regarded as the most honorable occupation of the German male.
Comitatus:  the Roman name for the German warrior band which surrounded a famous chieftain and which was a major part of German society.  The comitatus was an important forerunner of the medieval institution of feudalism.
Loyalty and hospitality were important virtues among the Germans.
Marriage appears to have been monogamous - in other words, one husband, one wife - and divorce was fairly easy, at least for German males.
Forms of marriage:
(1)  Monogamy:  a marriage in which there is a single sexual partner.  (One husband - one wife)
(2)  Polygamy:  a marriage in which there are multiple marriage partners.  (One husband has several wives or one wife has several husbands.)
The bard or storyteller was an important person, acting as entertainer, newscaster, and tribal historian.  Remember:  in a pre-literate society what history there is tends to be handed down by word of mouth.
The German system of wealth was based not on money but on how many cattle a person possessed.
There was some trade and some agriculture; however, since the Germans remained a pastoral nomadic people until after their conquest of the western Roman Empire, their economy was primarily based on the herding of animals, the gathering of wild food, and raiding.
The Germans, like most people of the ancient world, were polytheistic and we our names for four of the days of the week (Tuesday, Wednesday, Thursday, and Friday) from the names of their gods.
Polytheism:  believing in more than one god.
Monotheism:  believing in a single god.
German law, although not as important as Roman law, did have a significant impact upon European law in the early Middle Ages.  (For example, trial by battle and ordeal both came out of German law.)
Payment to victims for injury and death:
(1)  Bots - payment to a victim for injury
(2)  Wergeld (death money) - payment to a victim's family for his/her death
Forms of trial:
(1)  Compurgation (oath-taking)
(2)  Trial by Battle (a judicial duel)
(3)  Ordeal
In both trial by battle and by ordeal, the theory was that God would fight on the side of right and protect the innocent.  According to this theory, the fact that one combattant might be much larger and stronger than his opponent was irrelevant.
For the most part, the Germans were quiet during the Pax Romana.  During this period, a few were allowed to enter the Empire, mainly to serve in the army.  (For example, most emperors kept a body guard made up of German mercenaries.)  However, for the most part, Romans and Germans watched each other uneasily across the Rhine-Danube line.
Then, in the reign of Marcus Aurelius, the Germans began to make a concerted effort to push their way into the Empire.  Starting in 167 A. D., large numbers of them smashed through the Roman defenses, and ravaged the western territories, including Italy.   The emperor spent the rest of his life to drive them back.  As part of this effort, he attempted to reshape Rome's northern border in order to make it more easily defensible.  At first, Marcus Aurelius enjoyed success in implementing his plan.  Some Germans were driven back, others annihilated, until an unexpected disaster from the east negated his efforts.
Parthians:  the people who lived to the east of the Roman Empire.  While the Romans had been conquering the eastern Mediterranean in the last several centuries B. C., the Parthians had pushed into the Near East from the other direction.  Eventually, the two empires met and established an uneasy border east of Syria.  Over the centuries, the Romans and Parthians continued to clash.
Parthian War:  at the same time he was fighting the Germans in the north, Marcus Aurelius became involved in a war against Rome's ancient rival in the east.  Despite the fact that he was fighting a two front war, the emperor was victorious on the battlefield against both opponents.
Plague of the Antonines:  unfortunately for Rome, an extremely virulent plague broke out in the Near East and was carried back into the Roman Empire by soldiers returning from the Parthian War.  It became known as the Plague of the Antonines (the line of emperors to which Marcus Aurelius belonged) and, for fifteen years, it continued to ravagage the Empire, causing enormous damage to Roman society.  In its final year (180 A. D.), the plague took the life of the emperor.  The progressive weakening of the Empire brought on by this epidemic made it impossible for the emperor to complete his plans for reshaping the northern frontier.
Commodus:  the son of Marcus Aurelius whose succession to the imperial throne added to the disaster.  Commodus abandonned the efforts of his father and devoted himself to his bizarre pursuit of pleasure (including the slaughter of ostriches in the arena!)  He was finally assassinated in 192.
After the ravages of the plague, the death of Marcus Aurelius, and the disastrous reign of Commodus, Rome was never again strong enough for its army simply to drive the Germans out of the Empire.
New strategies for dealing with the Germans:
(1)  Roman treachery [No need to keep faith with barbarians!]
(2)  Psychological warfare [The continuing use of the myth of Roman invincibility to overawe the Germans.]
(3)  Bribery [When you can't beat or intimidate them, buy them off!]
(4)  Divide and Conquer [The Roman policy of keeping the Germans north of the Rhine-Danube line fighting among themselves.]
(5)  Resettlement
Rome's Resettlement Policy:  the Roman policy of resettling a certain number of Germans within the Roman Empire, and using the new immigrants to Rome's advantage.  Starting as early as the time of Caesar, some Germans had been permitted to enter the empire - whenever Rome felt she could use them!
Uses to which Rome put the Germans who entered the Empire:
(1)  Military service (esp. in the emperor's bodyguard)
(2)  Repopulation of underpopulated districts
(3)  A buffer against further penetration by the 'untamed' Germans across the rivers
Despite the existence of German resettlement throughout the Pax Romana, it only became a major Roman policy following the reign of Marcus Aurelius.  Rome decided that since it could no longer simply shut out the Germans, it had better incorporate them at a pace and in a manner which would benefit rather than disrupt the empire.  For several centuries, the policy was largely successful.  Germans entered the Empire slowly enough to be assimilated; or in other words, absorbed into Roman society.  They intermingled and intermarried with the Romans; and, as a result, they became increasingly Romanized.
At the same time that the newcomers were being Romanized, their presence was having a comparable effect upon the Romans.  The Roman Empire, especially in the western provinces, became increasingly Germanized.  In short, the Germanization of Rome began long before the Germans actually overran the western provinces.
Septimus Severus:  Roman general who came to the throne after the death of Commodus and established a new dynasty.  He and his family were interested primarily in the well-being of the soldiers who had put them in power and increasingly ignored the interests of other sectors of society.  When the Severan Dynasty collapsed in 235 A. D., all hell broke loose!
Anarchy of the Third Century:  a half century of nearly constant civil war which followed the collapse of the Severan Dynasty.  The army came to play a political role reminiscent of the late Roman Republic, with different military factions making and unmaking emperors with amazing rapidity (22 emperors in 50 years).  Whole regions of the Empire became independent of the central government; Germans and Persians smashed across the borders; commerce and industry declined; and, for a time, it looked as if the Empire would collapse.
Sassanid Dynasty:  a Persian family which overthrew the Parthians (also weakened by the plague) and established a reinvigorated Persian empire which increased the pressures on Rome's eastern frontier.
Shapur I:  the greatest Persian king who invaded the eastern Empire, took Antioch, and captured an emperor.
Finally, in the last decades of the 3rd century, a series of talented emperors, known as the Balkan Emperors, called a temporary halt to the process of disintegration.
Balkan Emperors:  so-called because the most talented came from the Balkan region, north of Greece, in the eastern provinces of the Empire, rather than from the western provinces which had produced most emperors up until this time.  The fact that they came from the east was symbolic of a larger reality:  Roman civilization in the western provinces was not as old or as deeply rooted; therefore, it was decaying more rapidly than in the east and, as a result, the center of gravity in the Roman world was shifting eastward.
This eastward shift is reflected in one of the emperor Constantine's most important acts - the creation of a new imperial city which began to surpass the ancient capital, Rome.
Constantinople:  established on the site of the ancient Greek city of Byzantium.  Constantine called it Nova Roma ["the New Rome"], but it soon became Constantinople in his honor.  For nearly a thousand years after the fall of Rome in the west, an Eastern Roman Empire - also known as the Byzantine Empire> [after the ancient name of the city] -  continued to be centered at Constanntinople.  Not until 1453 was it finally overrun by the Turks who renamed the capital city, Istanbul.
The Balkan emperors were jointly responsible for the final conversion of the Roman Empire into an oriental despotism, with its stress upon the divinity of the emperor, its elaborate ceremonies, and its use of jeweled crowns, thrones, and robes.
Diocletian:  the greatest Balkan emperor.  He, more than anyone else, was responsible for this move toward despotism.  (As we shall see in a later class, he also conducted the last and greatest persecution of Christianity.)  Diocletian was largely responsible for the idea of dividing the Roman Empire into an eastern and western half, ruled by co-emperors, as a means of achieving greater administrative efficiency.  Although the specific plan suggested by Diocletian did not catch on, there was an increasing tendency in the following century to have co-emperors, each presiding over part of the Empire.
The authoritarian changes instituted by the Balkan emperors were fairly successful in restoring order to the eastern half of the empire - at the price of what little freedom remained.  Whether or not they would have restored order in the west is debatable.  For in the west, the German tribes were once again on the move and time was running out.
In the two centuries following the death of Marcus Aurelius, German pressure had not been constant.  Pressure would build up after which, it would fall off for a time.  During this period, the high point of German activity had coincided with the Anarchy of the Third Century.  Then, at the end of the third century, this latest burst of activity ceased; and once again, for nearly 75 years, the Germans were relatively quiet.  This tapering off of German pressure gave the Roman Empire a much needed breathing space.
While hard fighting remained an essential part of Rome's strategy for dealing with the Germans, increasingly the Romans also had to use other means to keep the German menace in check.
Examples of this Germanization:
(1)  German modes of dress became popular.
(2)  Roman women died their hair blond or red or used wigs made from German hair.
(3)  German colonists moved onto deserted land in growing numbers, filling the gap caused by depopulation and the flight of farmers to the cities.
(4)  The Roman army which guarded the frontiers became progressively more German in make-up.
(5)  Germans took their place in the higher ranks of society.
(6)  At all levels, there was social intercourse and inter-marriage.
Had the movement of Germans into the empire continued at a manageable pace, it might have had far less sweeping results.  However, shortly before the year 400, German pressure on the frontier increased enormously.  Instead of one or two tribes attacking Rome, as had been the pattern in the past, waves of Germans all along the frontier swept across the borders.  The policy of assimilation collapsed as the trickle of Germans into the Empire became a flood.  Within a few decades, the entire westen half of the Roman world fell to the invaders.
Age of the Great Invasions (c. 400-550):  during this period, there was a vast migration of German tribes into the western provinces of the Roman Empire.
The Huns:  The German invasion was set in motion by the arrival of the Huns, a group of nomads from Central Asia who were ethnically related not to the Germans, but to the Mongols who, in the 13th century, would again sweep out of Mongolia under their great leader, Ghengis Khan.  The Huns setting the Germans in motion provides another example of the 'domino effect.'
The savage Huns terrorized everybody, including the Germans.  In 372, the Huns crossed the Volga River and subjected the Ostrogoths or 'East Goths'.
Background to the Battle of Adrianople:  The next people in the path of the Huns - the Visigoths or "West Goths" - appealed to Roman officials on the scene for permission to seek safety within the Empire.  Permission was granted and, in 376, a massive migration of Visigoths crossed the Danube River into the Roman world.  The Visigoths had agreed to serve in the army in return for food and land; however, either through corruption or incompetence, the Romans failed to keep their promises.  As a result, the newcomers went on a rampage and began to pillage surrounding territory.  The Romans now had to move against them militarily.
Battle of Adrianople (378 A. D.):  a battle, fought just north of Constantinople, where the Roman army sent out to bring the Visigoths back under control was annihilated.  The rash young emperor in command named Valens was killed along with 40,000 of his men.  Adrianople proved to be a decisive battle because the Romans lost more than just an emperor and an army.  The battle demonstrated to the Germans that they were fully capable of defeating the best which the Romans could send against them; consequently, the myth of Roman invincibility died at Adrianople.
Theodosius:  the last strong emperor of Rome who came to power right after the battle of Adrianople.  For a few years, he managed, through a skillful blend of fighting and negotiation, to keep the victorious Germans in check.  However, after his death (395), the old borders in the west ceased to exist as one after another, the German tribes swarmed into the Empire and established new homes on what had once been Roman territory.
Regions where major German tribes settled:
(1)  Visigoths:  Southern Gaul and Spain
(2)  Vandals:  North Africa
(3)  Angles and Saxons:  England [Angle land]
(4)  Ostrogoths:  Italy
(5)  Lombards:  Italy [replaced the Ostrogoths there in the mid-6th century]
Alaric:  leader of the Visigoths who sacked Rome in 410 - the first time this had happened in 800 years.
Vandal Sack of Rome:  In 455, the Vandals sacked Rome for a second time within half a century.  Our word "vandal", meaning one who destroys property, comes from this event.
Attila:  the famous leader of the Huns who, in the mid-5th century, led his people as far west as the region around Paris, leaving a trail of destruction.  Since both the Germans and Romans hated the Huns, they formed an alliance and defeated Attila's army.  Afterwards, Attila marched south into Italy and threatened Rome.  However, following his death in 453, the empire of the Huns collapsed.
Battle of Chalons (451):  the battle at which the Romans and Germans defeated the Huns.
Iin the face of the German invasions, Roman rule in the west became a joke.  The emperors after Theodosius became mere puppets of the conquering German leaders.
Romulus Augustulus:  son of a German general who, while still an infant, was proclaimed emperor.  He was deposed in 476 A. D.  As a result, this has become the traditional date for the fall of Rome in the west; as well as the beginning of the Middle Ages.
Odovaker:  German general who deposed the last western emperor and declared himself king of Italy.
Note:  the German invasions did not bring down the Roman Empire in the east (otherwise known as the Byzantine Empire) which lasted for another thousand years.
Generalizations concerning barbarian invasions:
(1)  They often occur over a very long period - perhaps centuries.
(2)  They tend to be gradual at the beginning.
(3)  At some point, the pace of invasion accelerates to become a flood.
(4)  Barbarians rarely overthrow a culture which is at its peak; instead, they are successful against a culture which is experiencing internal decay.
(5)  During and after the invasion, there is usually a cultural decline.  Rarely, however, is there an absolute collapse.
(6)  Each new wave of barbarians entering a civilized region tends to bring with it further cultural decline.
(7)  If one wave of invaders follows another too rapidly, the decline is much more extreme.
(8)  Eventually, however, through the related processes of cultural diffusion and blending, a new culture arises from the ashes of the earlier one.
 The relationship between German and Roman culture is an example of three inter-related processes at work:
(1)  Cultural diffusion
(2)  Cultural borrowing
(3)  Cultural blending
Cultural diffusion:  the process by which cultural features of one society spread to another society.  This process, which almost always occurs when two or more societies come in contact, may be accomplished by peaceful contact (trade, travel, migration) or military contact (conquest).  Cultural diffusion is usually a two way street;  in other words, when two societies come in contact, each one influences the other.  Normally, the society with a higher culture has the greater influence: however, influence also flows in the opposite direction - from the lower culture to the higher one - and this influence may also be considerable.
Cultural borrowing:  when one society borrows elements from the culture of another society.  This is simply cultural diffusion from the borrowers viewpoint.
Cultural blending:  when elements of one culture mingle or 'blend' with elements of another culture to form a new cultural pattern. Rarely does one society simply take over the culture of another society.  What usually happens is that the borrower takes over certain cultural features, and then weaves them into his own culture.  This weaving of cultural elements into one's own culture is is the process of cultural blending. 
Generalizations concerning Cultural Diffusion:
(1)  For cultural diffusion to take place, several (two or more) societies must co-exist and have contact.
(2)  Usually, the society with a higher culture has greater influence (or, to put it another way, there is greater diffusion from the higher culture to the lower one than vice versa.)
(3)  Cultural diffusion often takes place as a result of political conquest.
(4)  However, it is not always the conquering power whose culture dominates.  (Not infrequently, a people at a relatively lower cultural level overrun a weaker, but more highly cultured society; in which case, the higher culture may dominate in the resulting cultural blend.)
Examples mentioned in class:
The Roman conquest of western Europe and the spread of Roman culture into this region is an example of generalization # 3.
The Roman conquest of the Greeks and the German conquest of the Western Roman Empire are examples of generalization # 4.
The Ostrogothic chief, Theodoric, is a perfect example of a powerful German leader adopting Roman culture.