noun
troops in ambush; ambush force; ambush
Military use for soldiers or a force hidden in advance to attack suddenly; it refers especially to the hidden force itself.
山道に伏兵を配置した。
They placed troops in ambush on the mountain road.
部隊は敵の伏兵に襲われた
The unit was attacked by enemy troops lying in ambush.
noun
unexpected opponent; unexpected obstacle; surprise rival
Figurative use for someone or something not expected to matter but that suddenly becomes a serious rival, opposition, or obstacle.
選挙戦では無名の新人が伏兵になった。
In the election campaign, an unknown newcomer became an unexpected rival.
大会運営の伏兵は突然の大雨だった。
The unexpected obstacle in running the tournament was a sudden heavy rain.