April, May, and June 1958 were occupied with leave, upkeep, and local operations in the San Diego area. "Union" underwent a material inspection during July, and a resupply expedition to the Pribilof Islands scheduled for August was cancelled due to the Lebanon crisis which broke in early July. During September, the ship took part in "Phiblex 2–59," a full-scale landing exercise for the 1st Marine Division at Camp Pendleton.