Four-party Vietnam peace pacts were signed in Paris on 27 January. Subsequently, North Vietnam released some 590 U.S. prisoners by 1 April. The last U.S. troops left Vietnam on 29 March.
Citation:
Richert, Lucas Paul. "Vietnam Peace talks conclude".
The Literary Encyclopedia. First published 01 November 2008
[http://litencyc.com/php/stopics.php?rec=true&UID=5694, accessed 25 May 2013.]