Ministry of War Transport

While the American war merchant fleet mainly consisted of the famous Liberty ships, the British Ministry of War Transport had the so-called 'EMPIRE' ships.An Empire ship is a merchant ship that was given a name beginning with 'Empire' in service to the United Kingdom government during and after World War II. Most were used by the Ministry of War Transport (MoWT), which owned and subcontracted their operation to various shipping companies of the British Merchant Navy.
Empire ships came from two main sources: new construction and capture and seizure. New Empire ships were built for the MoWT or obtained from the United States to increase Britain's shipping capacity and reduce losses to German U-boats, commercial raiders, bombing raids and other enemy actions in the tonnage war Germany waged against British maritime transport compensation all over the world. . Others were seized by enemy forces and others were acquired by requisition or normal purchase or lease.
The fleet of 'EMPIRE' ships represented a huge undertaking that included classes of freighters, tankers, aircraft carriers, fast freighters, tank landing ships, Deep Sea Salvage and Rescue Tugs and several other categories. Total production was in the hundreds.
Empire ships supplemented the normal British merchant fleet in peacetime, increasing wartime numbers to 12,000, then the largest merchant fleet in the world. About 4,000 ships in the British register were lost between 1939 and 1945, a significant number sunk during the Battle of the Atlantic.
Source: https://en.wikipedia.org