. . "1st Engineer Combat Battalion" . "1846" . "1st Engineer Battalion (United States)" . . "1st" . . "1st Engineer Battalion)" . . . . . "1st Engineer Battalion (United States)" . . . . . . . . "1st Engineer Battalion" . . . . . "Always First" . "120px" . . . "1st Brigade Engineer Battalion" . . . "1st Engineer Regiment" . "Battalion, U.S. engineers" . . "United States Engineer Battalion" . . "U.S. Engineer Battalion" . "US 1st Engineer Battalion" . "21st Engineers" . . . . . "Battalion United States Engineers" . "U.S. Battalion" . . . . "1st Engineers" . . . . "Battalion U.S. Engineers" .