On 17 May 1968, detachments of 35 men and 5 vehicles from each battalion and separate companies departed from their station at Sioux City, IA, Topeka, Hiawatha, and Kansas City, KS.
On 19 May, the advance detachment of 74 vehicles and 237 men entered Fort Carson. At Fort Carson, first reports were received in July 1968 to levy individuals of the Brigade for service in other units in the States or overseas. The principal destination was the Republic of Vietnam. Men on orders began their Preparation for Overseas Replacement training (POR). "The levies continued on a monthly basis. Each time a levy came down, the number of men increased until 2,301 officers and enlisted men on orders. The levying of Brigade personnel continued until May, 1969. At first, the levies took support-type troops whose skills were needed, such as medics, wiremen, and other critical MOS. Infantry Captains were among the first officers to get orders. Finally, about 60 percent of the enlisted men and 95 percent of the officers of the 69th were levied.
All but a few went to Vietnam. Of the infantry troops, primarily 11C's were being called. These heavy weapons personnel came primarily from the 1st and 2nd Battalions of the 137th Infantry Regiment. In addition, the mechanized battalion from Iowa was hit hard by the replacement levies. In fact, none of the original unit escaped the levy."
The first troops from the 69th Infantry Brigade arrived in Vietnam late in October 1968. "They took their place alongside Regular Army troops. They did the job that was asked and did it well." The 1st Brigade of the 5th Infantry Division was being posted to Vietnam, and the 69th phased into the force structure of the 5th Division as a divisional type brigade. Members of the brigade were assigned to different sections of the 5th Division and other units at Fort Carson.
In December 1968, The Department of the Army announced an early release plan for the 69th Infantry Brigade, the new date was the 15 December 1969. "On 25 November 1969, the colors of the 69th were cased in a review before LTG Vernon P. Mock, Commanding General of the Fifth United States Army. General Mock praised the men of the 69th for their dedication ability and lauded their accomplishments both at Fort Carson and at other duty stations. At the conclusion of the review, General Mock decorated General Breidenthal and Colonel Kennedy with the Legion of Merit. Then the 69th took the review of the newly organized 4th Brigade which was to be its replacement in the 5th Division." "It was a sad time, however, for many units which had lost men during the 19-month period of active duty. Thirty-seven members of the 69th Brigade were killed in Action in Vietnam." Five died by accident in training.
On 12 December 1969, demobilization ceremonies were held in Kansas and in Iowa. The 69th Infantry Brigade was reverted to state control on 13 December 1969, at 0001 hours.