It was a ubiquitous part of the rations of many allied nations, but I'm wondering how SPAM (Hormel states all caps is proper BTW) was prepared in US forces. There are only so many common ways to serve it, and I'm sure the various military branches had recipes to follow. Was it just sliced and fried, or did it find it's way into different dishes?
As a preserved protein, military cooks could be as creative as the situation required. It was served with eggs, rice, potatoes, sometimes all by itself. It required no cooking, and in reality, no heating. In a bunker or foxhole, it would do in a pinch if no other rations were handy.
Also, civilians in US occupied areas in the Pacific both theaters adopted it into their own cuisine, as food was often in short supply, and the military and supply convoys supplemented their diet however it could. SPAM sushi is still found on some Japanese menus, and McDonald's serves SPAM items to this day in Hawaii and other Pacific area locations.
2nd edit - SPAM is still going strong in the military. This story describes a British Army cook having to feed his troops in Afghanistan for 6 weeks in 2010 on SPAM based meals after supply lines were cut. He got very creative.