 On 14 July, both ships were reassigned to Battleship Division 2 and Nagato became the flagship of the 1st Fleet. She remained in Japanese waters training until August 1942. Mutsu was transferred to the Advance Force of the 2nd Fleet on 9 August, and departed Yokosuka two days later to support operations during the Guadalcanal Campaign. She arrived at Truk on 17 August. On 20 August, while sailing from Truk to rendezvous with the main body of Vice Admiral Chūichi Nagumo's 3rd Fleet, Mutsu, the heavy cruiser Atago, and escorting destroyers unsuccessfully attempted to locate the escort carrier USS Long Island in response to a flying boat detection of the American ship.
