In war, you would need to rely on your buddies. But, your whole platoon is captured and you need to rescue them before they get killed by the enemies. For the meantime, you would need to rely on yourself as there is no other option. In this game, you are the commander and you would need to rescue your comrade and defeat enemies. Collect some cash too, to be able to buy some upgrades. You might not be able to finish the game in your first try, but that would earn you money, which you can use to buy upgrades.