External Factors:
1. Barbarian Invasions: Germanic tribes, such as the Visigoths, Ostrogoths, Vandals, and Huns, launched repeated attacks on the Roman Empire from the 4th century onward. These invasions put pressure on the empire's borders and drained its resources.
2. Rise of Christianity: The adoption of Christianity as the official religion of the Roman Empire in the 4th century led to a shift in focus away from traditional Roman values and traditions. This contributed to a decline in civic virtue and a weakening of the military spirit.
Internal Factors:
1. Political Instability: The Roman Empire experienced a period of political instability in the 4th and 5th centuries, with frequent civil wars and power struggles. This led to a decline in central authority and a lack of effective leadership.
2. Economic Decline: The empire's economy suffered from a combination of factors, including over-taxation, inflation, and the loss of trade routes. The decline in revenue and economic productivity made it difficult to maintain the military and defend the empire's borders.
3. Social Disintegration: Roman society experienced social divisions and a decline in civic participation. The wealthy elites became increasingly isolated from the common people, leading to a breakdown in social cohesion and a loss of loyalty to the empire.
4. Military Decline: The Roman military, once a formidable force, underwent a decline in discipline, training, and equipment. The empire increasingly relied on Germanic mercenaries, who often proved unreliable and had divided loyalties.
5. Administrative Corruption: Corruption became widespread in the Roman administration, leading to a decline in efficiency and a loss of public trust. This weakened the empire's ability to respond effectively to challenges.
Ultimately, a combination of these factors contributed to the gradual decline and eventual collapse of the Western Roman Empire. The empire's final blow came in 476 CE when the Germanic warlord Odoacer deposed the last Roman emperor, Romulus Augustulus, and established his own rule in Italy.