The numeral 38 was chosen for the Post, which represents the 38th parallel. The 38th parallel became the imagined border between North and Sooth Korea. The DMZ (demilitarized zone) runs near the 38th parallel, covering 248 kilometers. American and South Korean soldiers patrol this line along the South Korean side while North Korean soldiers patrol along the North Korean side. The name of the post was in honor of Colonel Lewis L. Millett. Millett was a U.S. Army officer who received the Medal of Honor during the Korean War for leading the last major American bayonet charge. On February 7, 1951, during the fighting near Osan, South Korea, Millett's unit encountered Communist troops atop Hill 180. As company commander, after ordering his men to fix bayonets, Millett charged up the hill in front of his men in the face of heavy fire, blasting away with his carbine, throwing grenades and most spectacularly wielding his bayonet whe he encountered three enemty soldiers in a V-shape gun positions. Millry was wounded by grenade fragments during the fight but his men captured the hill. President Harry S. Truman in July 1951 presented him with the Medal of Honor. As the citation put it, "His dauntless leadership and personal courage so inspired his men that they stormed into hostile position and used their bayonets with such lethal affet that the enemy fled in wild disorder".

On May 7, 2015 a temporary charter was granted to the Colonel Lewis L. Millett Memorial, Post 38, South Korea by the National Executive Committee of the American Legion. Sixteen Legionaries are listed on the temporary charter: Michael Napsey, William Wight, Steven Tharp, Gary Hewitt, Brian Daiello, Casey Roberts, William Black Jr, Donald Wong, William Beatty, Anthony Biagianti, Robert Hochmuth, David Hill, Angelo Rotger, David Sisney, Michael Higgins, and Albert Deloney III. Colonel Lewis L. Millett Memorial, Post 38, South Korea was granted its permanent charter on October 14, 2015.

The American Legion, Col. Lewis L. Millet Post 38 is located in Osan Air Base, South Korea and encompasses Area North, Seoul and Osan and is under the Department of the Philippines. Post 38 is the first established American Legion Post in South Korea.