The boats were lightly-built using mahogany, powered by two petrol engines, but lacked transverse bulkheads within the hull to mitigate leaks.

When Yugoslavia entered World War II due to the German-led Axis invasion of the country in April 1941, both boats were captured by Italian forces, after an abortive attempt by one crew to join the fledgling Navy of the Independent State of Croatia.

The boats were commissioned in the Royal Italian Navy and operated with a squadron out of the Dalmatian port of Šibenik, where they had been based pre-war.

Large numbers of 55-foot-long (17 m) Coastal Motor Boats (CMBs) had been produced in the UK between 1917 and 1922 for the Royal Navy, and they were also sold to overseas customers in the interwar period.

[1] In 1926, the KM ordered two MTBs based on John I. Thornycroft & Company's existing class of 55 ft CMBs,[4] but the Yugoslav boats were longer.

In order to save on weight, they had no transverse bulkheads to mitigate leaks,[5] and the engines and petrol tanks took up the majority of the hull space.

An open cockpit for steering was located amidships, and immediately fore and aft of it were columns on which twin machine guns could be mounted.

An auxiliary 4-cylinder petrol engine, coupled to the port shaft, was fitted for cruising, at a speed of up to 8 kn (15 km/h; 9.2 mph).

[8] For anti-aircraft and close defence purposes, a pair of 7.7-millimetre (.303 in) Lewis machine guns on a twin mount were carried, which could be attached to the columns either forward or aft of the cockpit as needed.

[10][11] They were commissioned into the KM as torpedo boats, Serbo-Croatian: torpedni čamci, TČ, named Uskok (TČ1) and Četnik (TČ2).

Četnik sailed to Divulje near Split – by Popović's second-in-command, poručnik fregate (Lieutenant) Velimir Škorpik – ostensibly to join the nascent Navy of the Independent State of Croatia (Croatian: Ratna Mornarica Nezavisne Države Hrvatske, RMNDH).

[15] She was lost on 19 April 1942 in heavy seas near the island of Mljet after the rivets in her hull plating failed due to engine vibrations.