Which war is Jack Arnold described as a veteran of?

Jack Arnold is described as a Korean War veteran on The Wonder Years.

The detail helps explain Jack’s stern outlook and his place within the Arnold family. He belongs to the generation that grew up during the Great Depression and came of age amid military service and postwar American expectations. The series portrays him as a former U.S. Marine, and photographs show him in a military uniform with the rank of First Lieutenant.

Jack’s wartime background also shapes his reaction to the political and cultural upheavals Kevin witnesses during the late 1960s and early 1970s. He is conservative, disciplined, and uncomfortable with the younger generation’s changing attitudes, while his children increasingly question the assumptions he inherited.

The Korean War lasted from 1950 to 1953, placing Jack’s military experience before the Vietnam-era events that appear in the series. Vietnam is therefore an easy but incorrect mix-up: the show’s setting includes that conflict, but Jack is identified specifically as a Korean War veteran. World War II and the Gulf War are also incorrect for his character.