Hey guys!

I was wondering about this question when I played my first game ever with the core set yesterday:

If I had a a guy with 1 hitpoint blocking 5 guys with 1 power and 1 hitpoint. The damage assigned on my guy is 1 and 4 on my capital and after the assigning I buff my guy to 6 hit points in some way...what would happen to the damage on my capital? Would it all shift to my now 6 hit point guy, or would he simply survive combat and totally annihilate 1 guy of my opponent?

Thanks in advance!