Final answer:
Incorporating Germanic tribes into the Roman army led to issues of loyalty, cultural integration, and military cohesion, contributing factors to the weakening of Roman military power and the instabilities along its borders.
Step-by-step explanation:
Integrating members of Germanic tribes into the Roman army posed several problems for the Roman Empire. One issue was the Germanic perception of treaties, which they believed only lasted as long as the emperor who made them. Consequently, the death of an emperor often led to border incursions and conflicts. There were also notable successes, as some Germanic individuals, such as Stilicho, rose to high ranks and performed admirably in Roman service.
Rome's reliance on Germanic soldiers increased over time, but the diverse military sometimes suffered from a lack of cohesion and common identity. This, along with raids and invasions from Germanic tribes, like the pivotal defeat in the Teutoburg Forest, and the crossing of the frozen Rhine in 406 CE, showed the declining integration and control within the army. Ultimately, this reliance contributed to the weakening of Rome's military power and authority over its territories.
Despite incidents of peaceful coexistence and cultural integration, the challenges of integrating Germanic soldiers highlight the shifting dynamics and eventual breakdown of Roman military and border stability.