Navy Pier goes to war - twice.

WWI:
You may have read in another post how part of the east end of the pier was used as a temporary military prison for draft dodgers.   The other tower at that end of the pier was also enlisted for military use - as a carrier-pigeon station.

WWII:

When it came to war production, Chicago, like many urban centers, stepped up to the task at hand.   Did you know that more than 50 area companies manufactured parts for the B-29 bomber?   Did you know that the Chicago Roller Skate Company converted their plant from making skates to the manufacturing of nose sections for those bombers?   Local jukebox manufacturer, Rock-Ola, switched over to rifle production.  Navy Pier was enlisted to train troops for aircraft carrier duty as well as other military duties.   Many a young pilot learned their take-offs and landings on Lake Michigan on two ships converted/rigged to act as aircraft carriers.  One of those pilots happened to be a young George H W Bush.