I need the name of a movie?

I watched this movie before on HBO, the movie was about World War 2, a minor battle in a mountain with snow.

In the beginning of the movie, this soldier was carrying his wounded comrade back from the battle field, then he gave him a cigarette and then kill him, put him out of misery. Then, the story move on to a point where he got assigned a new mission, with new comrades. At the end of the movie, the same situation happened again, only different roles, the soldier who executed his comrades before was badly wounded and he was being carried back by a new recruit, who wouldn't "put him out of misery" by his new comrade.

If it ring a bell to you, please let me know the name of the movie, thanks.