In February of 1944, the Marine Raiders were disbanded. Keller met and subsequently married his wife, Ruby O'Halloran, while he was home on leave. Keller was next assigned to Easy (E) Company, 2nd Battalion, 28th Marine Regiment, 5th Marine Division which was activated at Camp Pendleton in 1944. In September, the division was sent to Camp Tarawa near Hilo, Hawaii, for further training to prepare for the invasion of Iwo Jima. In January 1945, the division left Hawaii and sailed for Iwo Jima. Keller participated in the battle of Iwo Jima, which began on February 19 and ended on March 26. On February 23, he was part of the 40-man patrol that ascended Mount Suribachi and raised the Second Battalion's flag on top. Later that day, he was one of the six Marines that raised a second and larger flag on top.