..was wondering that one:wacko: too..? From the 45 Infantry Divion Museum website:
For the first 15 years of its existence, members of the 45th Infantry Division proudly wore on their left shoulders an ancient American Indian symbol of good luck, most commonly referred to as the swastika. The insignia served as recognition of the great number of Native Americans proudly serving in the 45th Infantry Division. The yellow swastika on a square background of red symbolized the Spanish Heritage of the 4 Southwestern states that made up the membership of the 45th—Oklahoma, New Mexico, Colorado, and Arizona. A similar symbol was adopted by the Nazi party in the late 1920’s, and as the N.S.D.A.P. rose to power in 1933 the symbol became so closely associated with fascist socialism that it had to be abandoned as the insignia of the 45th Infantry Division.
For many months division members wore no insignia, while the design for a new emblem was being explored. The 45th Infantry Division held a contest to assist in selection of the new insignia and many designs were submitted. The contest was overseen by a board of officers who eventually determined the Thunderbird would become the new insignia of the 45th Infantry Division. In keeping with the tradition formerly established, it was also decided to maintain the same colors and design of the original insignia.
In 1939 after approval of the Commanding General, Eighth Corps Area, and the Chief of the National Guard Bureau, the Thunderbird design was officially approved by the War Department and authorized for manufacture and wear. The document approving the design, which was to become famous in World War II and the Korean War, stated that, the Thunderbird was a Native American symbol signifying "sacred bearer of happiness unlimited."