Marine War Dogs - Sniffing Out Hidden Defenders

Iwo Jima's natural terrain helped the Japanese defenders stay hidden, so Marines used dogs to find them: 

WAR DOGS and their handlers stood sentry duty, manned outposts, and accompanied patrols. If an enemy lurks in this cave, [the] dog will signal.

Credits

US Navy photo, from Iwo Jima:  Amphibious Epic, United States Marine Corps Historical Monograph, by Lt. Col. Whitman S. Bartley, USMC.

Image located in Chapter VII - "5th Division on the Left (D+6 - D+19)," at page 139.