Hamilton Khaki Military

Hamilton Khaki Military - Manual Wind

I've been searching for vintage Hamilton for a long time until my friend also a collector found me this Hamilton, actually I'm not so happy with the size its only 34mm, but the mint condition and well preserve of manual wind 17 jewels american tradition with swiss made movement make me feel like I was one of the army officer having this watch back in the war era.
 But simple question in my head, how come they made such a small diameter watch for military, how if they cant see it well during war haha.

 

Self Collection