To dream of an army represents a rigid stance or belief system. Persistent beliefs or values in the face of adversity. It may reflect your need to muster up all your strength to endure a hardship. Buckling down to deal with a problem. Following strict rules or an important schedule. Punctuality. Alternatively, it may reflect a strong sense of loyalty to a team.
Negatively, an army may symbolize a stubborn attitude or a big grudge.
Example: A girl dreamed of the Russian army coming towards her. In real life her friend was very stubbornly disagreeing with her.
Example 2: A father dreamed of living on an army base. In real life he was setting very strict rules for his son to live in his home.