1. Gallic Wars (58-51 BC): Julius Caesar led the Roman legions against various Gallic tribes in what is now France, conquering the region and expanding the Roman territory.
2. Germanic Invasions: From the 2nd to the 5th centuries AD, Germanic tribes, including the Visigoths, Ostrogoths, Vandals, and Franks, launched numerous attacks and invasions against the Roman Empire. These incursions eventually contributed to the fall of the Western Roman Empire.
3. Parthian Wars (1st century BC - 3rd century AD): The Parthian Empire, based in what is now Iran, clashed with the Romans for control of territories in the Middle East and Armenia. The wars resulted in fluctuating control over the disputed regions.
4. Sassanid Wars (3rd - 7th centuries AD): The Sassanid Persian Empire succeeded the Parthians and continued to engage in conflicts with the Roman Empire. The Sassanids captured Roman territories and even conquered Jerusalem briefly in the 7th century.
5. Gothic Wars (535-554 AD): The Ostrogothic Kingdom in Italy was challenged by the Byzantine Empire, which sought to regain control over the Western Roman territories. The Gothic Wars involved several battles and sieges, ultimately resulting in the Byzantine reconquest of Italy.
6. Arab Conquests (7th century AD): In the 7th century, Muslim Arab forces launched a rapid expansion, conquering vast parts of the Middle East, North Africa, and even parts of Spain from the Byzantine Empire, which had inherited much of the Eastern Roman territories.
7. Viking Raids (8th - 11th centuries AD): The Vikings, hailing from Scandinavia, conducted raids and invasions on various parts of Europe, including territories under Roman control. They plundered coastal settlements, including Britain and France, and even raided Rome itself in the 9th century.
8. Norman Invasion of England (1066 AD): Although not directly targeting the Roman Empire, the Norman invasion of England in 1066 marked the end of Anglo-Saxon rule and brought significant political and cultural changes to former Roman territories in Britain.
These are just a few examples of the numerous invasions and attacks faced by the Roman Empire during its existence. The constant pressure from various groups and civilizations contributed to the decline and eventual fall of the Western Roman Empire in 476 AD, while the Eastern Roman (Byzantine) Empire survived for another thousand years.