The I class was a class

Ship class

A ship class is a group of ships of a similar design. This is distinct from a ship-type, which might reflect a similarity of tonnage or intended use. For example, the is a nuclear aircraft carrier of the Nimitz class....

 of eight destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

s plus a flotilla leader

Flotilla leader

A flotilla leader was a warship suitable for commanding a flotilla of destroyers or other small warships, typically a small cruiser or a large destroyer...

 of the British Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 ordered under the 1935 naval programme, laid down in 1936 and completed in 1937 and 1938. Four similar ships were ordered by the Turkish Navy

Turkish Navy

The Turkish Navy is the naval warfare service branch of the Turkish Armed Forces.- Ottoman fleet after Mudros :Following the demise of the Ottoman Empire in the aftermath of World War I, on November 3, 1918, the fleet commander of the Ottoman Navy, Liva Amiral Arif Pasha, ordered all flags to be...

, of which two were purchased for the Royal Navy, bringing the total number of these ships in that service to 11—although three of the original ships had been lost by the time Inconstant and Ithuriel commissioned.