Congress only authorised two battleships in each fiscal year (thus the series of two-ship battleship classes), but the New Mexico class contained three ships. Mississippi and New Mexico were funded by Congress, but the new USS Idaho (BB 42) was funded by selling two older battleships (USS Mississippi BB 23 and USS Idaho BB 24) to Greece. The Idaho was commissioned into the US Navy on 24 March 1919. On 11 May 1943 the Idaho provided fire support for the invasion of Attu. She also supported the invasion of Kiska on 15 August, but the Japanese had evacuated the island in late July and there was no fighting. On 27 July the Idaho was involved in the 'battle of the pips' when she and the Mississippi fired 518 rounds of 14in shells at false radar contacts in near zero visibility. The ten active 'old' battleships were formed together in Task Force 54 (Rear Admiral Deyo). The Idaho was part of the Gunfire and Covering Group, and flagship of Group 4 (Idaho and West Virginia). The ten battleships were split into five groups: Group 1: Texas, Maryland; Group 2 Arkansas, Colorado; Group 3 Tennessee and Nevada; Group 4 Idaho, West Virginia; Group 5 New Mexico and New York.