The Consolidated aircraft was nonetheless a landmark in aviation history. When it went into production it was by far the most expensive and complicated combat aircraft which the world had seen. Despite this it was built in greater numbers than any other American aircraft in history, and in more versions (and for a wider range of purposes) than any other aircraft up to that time. It served on every front in World War II, and with now fewer than 15 Allied nations. In the words of the aviation writer Bill Gunston "it transcended anything seen previously in any sphere of endeavour".
The Liberator had an unusual layout - dictated by the slender Davis wing placed above its tall bomb bays. This wing was very efficient in cruising flight, which combined with the aircraft's great fuel capacity to give the B-24 longer effective range than any landplane of its day. But this layout meant that the main gears were also long. They were retracted outwards by electric motors - nearly everything on board being electrically-powered (an unprecedented characteristic of the Liberator).
Early versions supplied to the British RAF were judged not to be combat-ready, and were put into service as LB-30A transports. Improvements in defensive armament produced the RAF Liberator I, which was employed by RAF Coastal Command with ASV radar and a fixed battery of 20mm cannon. The RAF Liberator II (equivalent to the US Army Air Corps' Liberator B-24C) introduced powered gun-turrets and served as a bomber in the Middle East.
The B-24D was the first version produced in great numbers. It had turbocharged engines, increased fuel capacity and improved armament, as well as many detail changes. A total of 2,738 served with US Bomb Groups in Europe and the Pacific. The B-24D enabled Coastal Command and US forces to close the "mid-Atlantic gap" - in which U-boats had been able to operate with devastating effect beyond range of previous Allied anti-submarine aircraft.
To reiterate, the Liberator was in general longer-ranged and slightly faster than the B-17 Fortress, and could carry a heavier bomb load. But it was less stable, and more difficult to fly - and considerably more vulnerable to battle damage - than the B-17. This meant that the Fortress continued to be favoured over the Liberator in the strategic bombing campaign against Germany - in which tight formation-flying and resistance to damage were of paramount importance.
In the Pacific war, by contrast, distances to target were usually greater than in Europe, and Japanese air defences were, at least in general, not as effective as those of their German counterparts. This made the Liberator's virtues - especially its immense range - more important in the Pacific than its handling defects and vulnerability. It therefore tended to displace the B-17 Fortress in Pacific operations.
In any case the Liberator's superior range meant that the B-24 supplanted the Fortress in the maritime patrol role in the European theatre of war as well as in the Pacific. In fact it is arguable that the Liberator's greatest contribution to Allied victory was its vital work against U-boats in the Battle of the Atlantic.
Total production of the Liberator was the remarkable figure of 19,203 aircraft. As Bill Gunston comments "Their achievements were in proportion".