Troopships were often drafted from commercial shipping fleets, and were unable to land troops directly on shore, typically loading and unloading at a seaport or onto smaller vessels, either tenders or barges.
[2] The modern troopship has as long a history as passenger ships do, as most maritime nations enlisted their support in military operations (either by leasing the vessels or by impressing them into service) when their normal naval forces were deemed insufficient for the task.
Most major naval powers in the late 19th and early 20th centuries provided their domestic shipping lines with subsidies to build fast ocean liners capable of conversions to auxiliary cruisers during wartime.
Queen Mary holds the all-time record, with 15,740 troops on a single passage in late July 1943,[3] transporting a staggering 765,429 military personnel during the war.
[3] Large numbers of troopships were employed during World War II, including 220 "Limited Capacity" Liberty ship conversions, 30 Type C4 ship-based General G. O. Squier-class, a class of 84 Victory ship conversions, and a small number of Type-C3-S-A2 ship-based dedicated transports, and 15 classes of attack transports, of which some 400 alone were built.