The Watchismo watch-blog has a great pictorial history of military watch-armor used to protect watches in trench warfare:
Many military watches had a special feature for those "in the shit". A Trench Guard, grid or grille covered and protected the dial with medieval-style armor. Those not intended for war were classified as Hunter cased, often more decorative than protective.
See also:
History of slide-rule wristwatches
Early days of plastic watches
Mechanical "LED watch" from 1970
History of calculator watches
Steampunk watch
Belt-drive watch
Watch guts of great beauty
All-plastic watch movement from the 70s
Awesome, impractical, expensive watch
