He experienced his first encounter with the enemy on the battlefield.

He encountered the enemy on the battlefield.

He moved agilely to avoid the enemy bullets.

The enemy aircraft invaded our airspace.

We are ready to invade enemy territory.

We are conducting training to devise strategies against hypothetical enemies.

The signal from the cell phone relay-station in this area is weak.

Well then, I'm off.

He admitted that it is difficult to execute the plan, saying 'it is easier said than done.'

He said, 'It's difficult to make a life,' explaining the phrase 'When a man steps over the threshold, he has seven enemies.'