William Wyler began work on this film during 1944 as a counterpoint to his better-known film about the 8th Air Force, "Memphis Belle". While the latter concerned the strategic bombing campaign carried out by long-range, multi-engine bombers, the subject of "Thunderbolt" was tactical missions flown by single-engine, single-seat fighter-bombers. This was a very different war from that depicted in "Memphis Belle". For one thing, while strategic bomber crews could expect to be rotated home after completing 25 missions, the fighter-bomber pilots were flying literally hundreds of missions, frequently carrying out several during the course of a single day.
The film chronicles a brief period with one of several fighter-bomber groups based on the island of Corsica, about 60 miles west of the Italian mainland. Incidentally, this was the same island where Joseph Heller was based, and which inspired him to write his famous novel, "Catch-22". The only difference is that "Thunderbolt" was not filmed with a Medium Bomber Group, such as Heller served in, but with a Fighter-Bomber Group.
The fighter-bombers featured in the film are P-47s, to which the Army Air Force gave the emotive name of "Thunderbolt". However, to those who flew them, the P-47 was invariably known as "The Jug", partly due to it's rotund shape, but more especially as a contraction of the word "Juggernaut". For a Juggernaut was precisely what the P-47 was. The Jug was the largest single-seat fighter to serve during WW-II. It carried eight 12.7-mm machine guns along with a heavy load of bombs or rockets, and was capable of bringing it's pilot home after absorbing a considerable amount of battle damage. Unlike any other fighters of that time the Jug had an air-cooled engine, which meant that it's pilot did not have to worry about a liquid cooling system that was vulnerable to damage from enemy fire. Because of those characteristics the Jug came into it's own in the sort of low-level ground-attack missions shown in "Thunderbolt". In fact years later, when they began flying similar ground attack missions in Korea, a lot of veteran pilots regretted the fact that the Air Force had seen fit to scrap all of it's Jugs after WW-II ended.
"Thunderbolt" does not glamorize the lives of these fighter-bomber personnel. The narration is as terse as the subject matter. It was a brutal war, and that brutality is not watered down. To the men of the Fighter-Bomber Group this was merely a day-to-day job, with the difference that the working men shown in the film did not always live to see the next day. However, the film does go out of it's way to explain exactly what it was that they were trying to accomplish, and why it mattered. It is interesting to reflect that The Big Picture was something many of the members of the Fighter-Bomber Group probably did not entirely understand at the time. In short, these aircraft were engaged in cutting Italian road and rail communications in order to prevent the movement of war material to the German Army, so that the Allied Armies could break the stalemate in the mountains of Southern Italy. The mere fact that the stalemate was broken is proof of how effective the air campaign shown in the film actually was.
