It was late fall 1920 when Navy F5L and Curtiss H-16 seaplanes targeted the U.S.S. Indiana. The bombs hitting the battleship’s decks were duds, but the repercussions eventually heard around the world were very real.

Billy Mitchell was the upstart airman who claimed that an airplane and a couple of men could sink an armor-plated dreadnought that cost millions. His claims produced outrage in the military brass and unsettled industry leaders.

Testing on the Indiana showed that even inexperienced bombardiers hit the ship with a 40% accuracy rate and that “near misses” were even more concussive than direct hits. It was also shown that aerial bombs could severely damage heavy ship’s armor.

At first, the Navy tried to keep test results under wraps, but they eventually came out in highly publicized, contentious government hearings. Mitchell demanded, “…give us a collection of Navy ships, (and) we will prove that we can send them to the bottom.”

The Navy’s back was against the wall, and it was forced into an explosive chapter in aviation history. In July 1921, aerial bombardment testing led to the sinking of several classes of ships: submarines, destroyers, cruisers, and the “unsinkable” Ostfriesland. The battleship as the main line of defense was fast becoming a thing of the past, and the aircraft carrier, a totally new defensive arm, was born.