"The Man He Killed"

In the poem "The Man He Killed" by Thomas Hardy, I got the feeling the speaker didn't really want to kill the man but had to so he himself would not be killed. "I shot him dead because--/ because he was my foe"(lines 9-10). Also, he states "Had he and I but met/ by some old ancient inn,/ we should have sat us down to wet/ right many a nipperkin!"(1-4). I think the speaker is trying to say that if they were to have met under different circumstances they probably would have talked and been friends even and have a drink or two together, but this was war and they had to do what they had to do. This poem was quite interesting to read and learn that some had to kill just to survive and to fulfill their duties, not because they wanted to but because they had to.