text: He was fourth-billed in Behind the Rising Sun (1943), directed by Dmytryk, which was a huge box-office success then third-billed in The Iron Major (1943), with O'Brien, and Gangway for Tomorrow (1943).
  RKO promoted him to star status in Tender Comrade (1943), where he was Ginger Rogers' leading man, directed for the third time by Dmytryk. It was a big hit. Also popular was Marine Raiders (1944), in which Ryan co-starred again alongside O'Brien.
  World War II
  Ryan enlisted in the United States Marine Corps and served as a drill instructor from January 1944 to November 1945 at Camp Pendleton, in Southern California. At Camp Pendleton, he befriended writer and future director Richard Brooks, whose novel The Brick Foxhole he greatly admired. He also took up painting.
  Return to acting
  When Ryan was discharged from the Marine Corps, he returned to RKO. They immediately cast Ryan in the Randolph Scott western, Trail Street (1947), which was very popular. However, his next film made with Joan Bennett, The Woman on the Beach (1947) directed by Jean Renoir, lost money.
  Ryan's breakthrough role was as an anti-Semitic killer in the Dmytryk directed film noir Crossfire (1947), co-starring Robert Young, Robert Mitchum, and Gloria Grahame. Based on Brooks' novel, the film was highly successful at the box office, and received several Academy Award nominations including a Best Supporting Actor for Ryan's performance.