The Elco 80ft PT-556 was one of the 78 PT-486 batch of Elco PT boats, laid down on 18 September 1943 at the Elco shipyard in Bayonne, New Jersey, and launched on 20 October. The PT-556 was one of the select few Elco boats to receive the experimental Elco "Thunderbolt" quadruple Oerlikon autocannon mount. PT-556 was then assigned to serve in the Mediterranean and saw action along the northwestern coast of Italy and southern coast of France. Near the end of the war on 12 April 1945, PT-556 was transferred to the Soviet Union under Lend-Lease program. The boat received designation TK-435 and was assigned to the Northern Fleet. TK-435 would serve with the Red Navy until 3 September 1953 when it was decommissioned, and was struck from the naval list three years later on 25 June 1956. On 30 June that year, TK-435 was scuttled and disposed of off the coast of Kildin Island in accordance with the Lend-Lease agreement.

The Thunderbolt (PT-556) was introduced in Update 1.83 "Masters of the Sea". The PT-556’s most notable feature is the quadruple 20 mm Oerlikon autocannons mounted at the stern. These autocannons provide a very dense volume of fire, capable of making short work of any thin-skinned boats, but are offset by the awkward firing angle and low shell velocity, making it only effective at close range (below 2 km). Aside from this, the PT-556 is largely similar to other Elco boats, being generally fast and agile, but also quite frail, unable to take many hits from autocannons that many boats it commonly faces carry, and can be one-shotted by destroyer-calibre guns.