Military MC

The ML is a prince and commands an army under siege at one point. The FL helps by coming up with and executing a plan to sabotage the enemy's supplies.

ML is a captain in the North Korean army. The FL is captured by and eventually befriends his squad.

The ML is a top general. The FL sometimes helps him plan / strategize.

The ML is a prince who commands soldiers in battle. The FL is a sorceress who fights in battles.

ML works his way up from essentially a gangster (canal gang) to low-level soldier to top general.

The ML is a Captain in the  US Marine Corps and the acting consul for the US legation in Korea.

Broader military theme. The ML and SML are in the special forces.

Broader military theme. The FL cross dresses as a man and serves in the army for years with the ML. 

The FL, ML, SML, TML, etc. are students training to be military officers.

Broader military theme. The FL is a soldier. The ML is a smuggler / mercenary?

The ML is a general-prince. 

The ML is a prince who commands troops in battle during the Warring States period. The FL disguises herself as a soldier when travels back in time.

The ML is a general. The FL helps him win a war.