Silent, but Deadly

You fall to your knees and start complaining about all the sweat and blood burning your eyes. One of the sentries puts down his weapon to pick you up. The other sentry has his rifle pointing to the rest of the fire team. You ambush the unarmed sentry and force him into the armed sentry. The fire team jumps on top of both of them. With little struggle, the sentries have been terminated.
Cpl. Carter commends you on a job well done. "As fire team leader, I can only say you have fully redeemed yourself. I have to take that you are only a private."
"I try not to let the team down. I am going to make mistakes, I just hope that they are not of the fatal kind." You gain acceptance into the fire team.
"There is something that you must do. You must take out the observation tower. Once that is completed, you must take this flag," Cpl. Carter takes out an American flag from his backpack, "and raise it all the way up to let the rest of the platoon know that the mission is accomplished. Is that understood?"
Just as he gives you the instructions, footsteps and commotion can be heard echoing down the corridors. Cpl. Carter takes weapons and hands you one rifle. He tells you to move out. One problem...you do not know how to fire a rifle much less hold one.