External Threat of Roman Empire ● Sack of Rome by Gauls(390 BCE) ○ Gauls defeated Romans in Battle of Allia ■ Sacked city of Rome ■ Senate retreated ■ Rest of the city burned ■ 1000 pounds of gold to ransom the city ○ Roman first major defeat. ■ Gave fear of Northern Barbarian ■ Focused on stronger city defences ● Servian Wall Julius Caesar's Campaigns in the Gaul (58-50 BCE) ● Caesar invaded Gaul ○ Claim to protect Roman allies ○ Defeated multiple tribes ○ Defeated revolts ■ Siege of Alesia(52 BCE) ○ Expansion of Roman control to Rhine River ■ Gained wealth and popularity ■ Leads to civil war with Pompey ○ Foundation of Roman-Germanic Frontier conflicts ■ Lasts 400+ years Battle of Teutoburg Forest (9CE) ● Three Roman legion was annihilated in Teutoburg forest ○ Germany ● Arminus ○ Trained with Romans ○ Led the ambush ○ 20,000 Romans died ● Abandoned plans to conquer Germania ○ East of Rhine were unoccupied ○ Rhine river Roman frontier of north Marcomannic Wars(166-180 CE) ● Germanic tribe invades Roman province ○ During the time of plague ○ Internal unrest ● Long war for Rome ○ Balkan ● Marcus Aurelius ○ Created new Roman provinces ○ North of Danube ● First major Germanic pressure ● Weaken Rome’s frontier ○ Later germanic invasion in 3-5C