The photo was shot by Robert Hodierne in August, 1969.
Capt. William H. Gaylor, commander of Bravo Co., 4th Battalion, 31st Infantry Regiment, Americal Division, (left)prepares to lead his men into the Hiep Duc Valley, 35 miles south of Danang. His company had already been into the valley that morning and lost one man killed (KIA) and 13 wounded (WIA). Temperatures were well over 100 degrees. On the right is radio operator Spec. 4 James Sebestyen, 22, of the Bronx, N.Y.
http://vietnamphotography.com/units.php?pageNum_Recordset1=0&totalRows_Recordset1=76&UID=146
http://www.hodierne.com/hiepduc2.htm
More on Hodierne here:
http://news.richmond.edu/features/article/as/1614/professor-gets-back-to-war-photography-roots-in-afghanistan.html
http://www.combatoutpost.blogspot.com/