Week of December 30—January 5
On January 7, 1966 U.S. and Australian Army forces launched Operation CRIMP, a massive, joint search and destroy operation in a region about 25 miles northwest of Sài Gòn. Their objective was to locate and destroy the Việt Cộng headquarters and stronghold believed to be in the area. When allied forces located their objective, they discovered it actually was underground, contained in a vast network of tunnels. Some 7,500 documents and maps were found there, many of which revealed the names and locations of Việt Cộng agents and other actionable intelligence. It became one of the biggest allied intelligence coups of the war.
Approximately 8,000 men participated in Operation CRIMP, including forces from the U.S. Army 3d Brigade, 1st Infantry Division and the 173d Airborne Brigade, as well as the 1st Battalion, Royal Australian Regiment. These ground forces were also amply supported by artillery and U.S. airpower, including preparatory strikes by U.S. Air Force B-52 Stratofortresses.
The operation occurred in the Hố Bò Woods, a region that was largely open terrain punctuated by thick jungle and abandoned rubber plantations. Over the course of a week, CRIMP forces fought sporadic engagements with guerrillas and seized thousands of pounds of supplies, weapons, and rice in numerous caches. While firefights with Việt Cộng forces were intermittent, dense fields of booby traps and landmines caused numerous allied casualties, and in some units these devices killed more allied soldiers than did enemy fire.
Australian troops encountered the fiercest resistance of the operation on the afternoon of January 8. The next morning they found no enemy troops, but did locate the underground base that the Việt Cộng had been defending. This headquarters facility consisted of a vast complex of tunnels, which boasted barracks, hospitals, kitchens, storage depots, and munitions shops. Extensive searches of the complex also turned up vital intelligence, including lists of communist party members in South Vietnam, documents revealing the local Việt Cộng command structure, detailed maps, and the notebook of a senior political officer that became known as the “CRIMP Document.” Collectively, the tunnels contained one of the most important intelligence collections found by U.S. or allied forces during the war.
However, the majority of the Việt Cộng in CRIMP’s search area managed to escape. Approximately 130 Việt Cộng fighters were killed or captured. Combined U.S. and Australian losses were 23 killed and 102 wounded. The discovery of the Củ Chi Tunnels helped convince American commanders that massive search and destroy operations like CRIMP were unlikely to succeed if enemy combatants were hiding in such extensive underground complexes. U.S. forces therefore subtly shifted their strategy and resources toward finding and destroying these underground communist base areas and supply caches.1
1John M. Carland, United States Army in Vietnam: Combat Operations: Stemming the Tide, May 1965 to October 1966 (Washington, D.C.: Center of Military History, 2000), 169–73. Spencer C. Tucker, ed., The Encyclopedia of the Vietnam War: A Political, Social, and Military History (2nd edition; Santa Barbara, Ca.: ABC-CLIO, 2011), 245–46; David Burns Sigler, Vietnam Battle Chronology: U.S. Army and Marine Corps Combat Operations, 1965–1973 (Jefferson, NC: McFarland & Company, Inc., 1992), 11.