First Signal Brigade was activated on April 1, 1966

The History of the First Signal Brigade
The First Signal Brigade was activated on April 1, 1966, in the Republic of Vietnam. Its mission was one of the most complicated ever given to any signal unit in the history of warfare: to originate, install, operate, and maintain an incredible, complex communication system that fused tactical and strategic communications in Southeast Asia into a single, unified command. The creation of the brigade brought together three signal groups already in Southeast Asia along with other units into a single unified command, except those organic to field forces and divisions. The mission in Southeast Asia meant providing communications to forces scattered over more than 60,000 square miles of torrid jungle, mountain ranges and coastal lowland - much of which was under-populated and enemy-infested. One of the innovations that circumvented the difficult terrain and enemy situation was the introduction of an extensive, tropospheric scatter radio relay system, which provides numerous communications channels over distances of several hundred miles between sites. Other firsts include, first use of satellite communications in a combat zone and first use of automatic, digital message and data switches. At its peak, the brigade had more than 21,000 soldiers, with six signal groups, 22 signal battalions, and a large number of specialized communications agencies. This made it, at that time, the largest single brigade in the U.S. Army. The stand-down of 1st Signal Brigade was almost as significant as its buildup. Caught by the U.S. reduction-in-forces that affected our pullout from Southeast Asia, 1st Signal Brigade reduced its strength from 21,000 in 1968 to less than 1,300 by November 1972.
The departure of American forces from the Republic of Vietnam was accompanied by a decline in communications facilities needed to support them. Whole signal sites, from delicate communications gear to the buildings that housed them, had to be dismantled, packed and shipped to destinations around the world. More than $50 million worth of communications equipment and facilities were recovered between 1970 and 1972.