Until recently I knew very little about the US-made P-47 Thunderbolt (nicknamed the Jug - for obvious reasons - it's not exactly pretty). It was the biggest and heaviest single-engine fighter of World War II; and the fastest (propeller) combat aircraft at high altitudes and in a dive.
(P-47s were two or three times larger and heavier than most other well-known WWII fighters such as the Spitfire.)
Overshadowed in public perception by Spitfires, Mustangs, Messerschmitt 109s, Focke-Wulf 190s and Mitsubishi Zero - the Thunderbolt was nonetheless a truly great aeroplane, and I have been convinced by Greg - of the superb YouTube channel Greg's Airplanes and Automobiles * - that the P-47 was, more than any other craft, responsible for making D-Day possible.
Perhaps its only type-rival, in terms of war outcome influence; were the Hurricanes/ Spitfires (in that order) of the Battle of Britain.
As Greg describes in this very detailed and primary-source-evidenced video...
This is a fascinatingly different perspective than the usual one. I already knew that the doctrine of winning a major war by air bombing was false; and the truly colossal expenditure of highly trained men and expensive machines by UK Bomber Command was misplaced effort, that damaged the overall war capability of the UK.
But the US daylight bombing campaign is also put into a different light. The US heavy bombers are now seem mainly to function as lures for the Luftwaffe to attack, in order that German planes could be destroyed (and, especially, their pilots killed) by the (mostly) Thunderbolts - which were specifically designed to operate at high levels, with their powerful supercharged and turbocharged radial engines.
(In retrospect; it would have made more sense for the Germans to use only anti-aircraft Flak to attack the US bombers, rather than destroy the Luftwaffe and render themselves helpless by losing air superiority.)
The Thunderbolts had several other advantages in this role. Their armament of eight half-inch calibre heavy machine guns provided a tremendous weight and spread of bullets (each bullet of which was four times the weight of the .303 rounds used by Spitfires and Hurricanes in the Battle of Britain).
And the aircraft themselves were beloved by their pilots because they were exceptionally well protected from enemy fire (both by armour, and the sheer size of the surrounding aircraft); they were very strong, did not break up easily; and even when badly damaged could get the pilots back to safety in an almost miraculous fashion.
So, despite their 'homely' appearance - for their combination of being a deadly weapon and a pilot's friend - I think I would rather have flown a Thunderbolt than any other of the single seat Allied day fighters of WWII.
The Thunderbolts were gradually replaced by P-51 Mustangs in the long range bomber escort role (yet only after the Thunderbolts had done most of the 'heavy lifting' in Luftwaffe pilot destruction); but (as Greg makes clear) mainly because the Mustang was only one-third of the cost of a P-47; not because the Mustang was overall better at the job, which it wasn't.
(The P-51 was better than the P-47 in some relevant ways, but it was worse in others - as Greg evidences.)
After air superiority was achieved; the P-47s were then used as ground-attack fighter bombers - and performed superbly in this role; probably better overall than their nearest rival, the Hawker Typhoon.
But it is their decisive role in the crucial year from middle 1943 to the summer of 1944, doing a job that made possible the Western allies victory; that makes the Thunderbolt one of the most important warplanes ever.
* I strongly recommend this channel - but need to point-out that it is very techie/ engineering based. For instance; Greg's most commonly used words seem to be 'manifold pressure'; which I gather is A Good Thing for prop-driven aircraft.