During the Korean War General "Lightning Joe" Collins, Chief of Staff for the Army, asked a group of advisors what could be done to enhance the morale of the fighting Infantryman. It was decided that they would receive special insignia, so that everyone would know that the soldier was an Infantryman who would be fighting on the front lines.
A light-blue cord was created to be worn over the right shoulder of both officers and enlisted men. Also, light-blue plastic disks were issued to be placed behind the metal "crossed rifles" Infantry branch of service insignia disks. The new enhancements were first worn by the 3rd US Infantry Regiment ("The Old Guard"). The light-blue cord and disks became standard for all Infantrymen in 1952.
A light-blue cord was created to be worn over the right shoulder of both officers and enlisted men. Also, light-blue plastic disks were issued to be placed behind the metal "crossed rifles" Infantry branch of service insignia disks. The new enhancements were first worn by the 3rd US Infantry Regiment ("The Old Guard"). The light-blue cord and disks became standard for all Infantrymen in 1952.
Today, enlisted graduates of Infantry One Station Unit Training receive their blue cord at the "Turning Blue" ceremony held the day before their Initial Entry Training/OSUT graduation, or graduation from Infantry AIT. Other branches attend a similar ceremony called "Turning Green", but do not receive a shoulder cord.
Graduates of the Infantry Basic Officer Leaders Course must complete their two week-long final FTX with a 16 mile tactical road march and a mock company attack. Prior to graduation and out-processing, students have their "Blue Cord" ceremony at Freedom Hall where their blue cords are pinned on them by their platoon trainer Captain and NCOs. The staff sergeant or sergeant first class who pins on the blue cord then renders a salute recognizing the lieutenant's entry into the ranks of the Infantry.
Reference: Wikipedia
Graduates of the Infantry Basic Officer Leaders Course must complete their two week-long final FTX with a 16 mile tactical road march and a mock company attack. Prior to graduation and out-processing, students have their "Blue Cord" ceremony at Freedom Hall where their blue cords are pinned on them by their platoon trainer Captain and NCOs. The staff sergeant or sergeant first class who pins on the blue cord then renders a salute recognizing the lieutenant's entry into the ranks of the Infantry.
Reference: Wikipedia