This week, news is circulating that a WWII-era Grumman FM-2 Wildcat fighter plane has finished its restoration process. The rusted-out, broken-in-half airplane shell was pulled out of Lake Michigan in 2012. Since then, Air Zoo Aerospace and Science Museum has endured an estimated 50,000 labor hours – not to mention the $700,000 – it’s taken to cross the finish line. While reading about the plane, which has a fascinating story of its own, another tidbit caught my attention. More than 100 World War II-era American military planes are resting at the bottom of Lake Michigan to this day. How? Why?

The answer is folded into the war’s understory. Of course, one could spend a lifetime studying the war’s interior fissures. This one is fairly simple to understand, but it gives us an idea of just how much grit you had to have to hop into a Grumman in the early 1940s.

After Pearl Harbor, Lake Michigan was used as a military training ground for pilots. The country wasn’t quite ready for war, and the lake was much safer and more peaceful than the Atlantic, which the Germans actively patrolled. Of course, the Japanese had a presence in Pacific waters. To avoid the coasts, the Navy trained almost 15,000 pilots to take off and land on makeshift aircraft carriers placed on the lake’s waters.

Practice makes progress, right? As a result of failed training exercises, dozens of planes ended up crashing and sinking. The military didn’t recover them, so about 130 planes remain at the bottom of Lake Michigan, including fighter planes and dive bombers. Admirably, this is only a fraction of the training exercises the inexperienced pilots performed in qualifying rounds.

In 1943, an SBD Dauntless dive bomber sank shortly after it was commissioned. In 1991, it was recovered from the lake, restored, and placed on display in the National Museum of the Marine Corps.

The more recent recovery of the Grumman FM-2 Wildcat came with its own unique narrative. In mid-December 1944, the pilot was on his third round of takeoffs and landings when the plane’s engine locked up. The Wildcat fell off the back of the carrier with the pilot inside. The carrier’s rudder sheared the Wildcat in half when it hit the water. The pilot scrambled out and survived the ordeal. The plane, however, slept with the fishes until its recovery in 2012.

Below is a wonderful video explaining Lake Michigan’s role in the war, including a highlight of Air Zoo’s Grumman project.