I came across a really cool article about armor that the Americans wanted to use in World War I. Since it was before kevlar and modern body armor but still needed to stop bullets, they designed it to be similar to medieval armor. It looks terribly uncomfortable and ineffective. Just look at this helmet design:
The flaps could be opened when not in combat.
There are better pictures over at MilitaryHeadgear.com, and I suggest you check it out. Pretty cool!