The Allied "Watchtower" expeditionary force of 75 warships and transports, which included vessels from both the U.S. and Australia, assembled near Fiji on 26 July, and engaged in one rehearsal landing prior to leaving for Guadalcanal on July 31. Vandegrift was the overall commander of the 16,000 Allied (primarily U.S. Marine) ground forces involved in the landings and personally commanded the assault on Guadalcanal. In command of the 3,000 U.S. Marines set to land on Tulagi and the nearby islands of Florida, Gavutu, and Tanambogo was U.S. Brigadier General William H. Rupertus on the transport ship .