page_title: Operation Crimp
section_title: Tunnels of Cu Chi, 9 January 1966
hierarchical_section_title: Operation Crimp / Battle / Tunnels of Cu Chi, 9 January 1966
caption_attribution_description: English: Australian soldier in Viet Cong tunnel uncovered during Operation Crimp, Vietnam.
context_page_description: Operation Crimp, also known as the Battle of the Ho Bo Woods, was a joint US-Australian military operation during the Vietnam War, which took place 20 kilometres north of Cu Chi in Binh Duong Province, South Vietnam. The operation targeted a key Viet Cong headquarters that was believed to be concealed underground, and involved two brigades under the command of the US 1st Infantry Division, including the 1st Battalion, Royal Australian Regiment which was attached to the US 173rd Airborne Brigade. Heavy fighting resulted in significant casualties on both sides, but the combined American and Australian force was able to uncover an extensive tunnel network covering more than 200 kilometres.
  The operation was the largest allied military action mounted during the war in South Vietnam to that point, and the first fought at division level. Despite some success, the allied force was only able to partially clear the area and it remained a key communist transit and supply base throughout the war.
context_section_description: The process of breaking into and exploring the communist tunnels began on 9 January, with the objective now switching to the location, clearance and destruction of the tunnel complexes. Whereas standard US Army practice was to seal, blow up or otherwise attempt to render tunnel systems unusable with smoke, tear gas and explosives before quickly moving on, the Australians spent the next few days laboriously searching and mapping the complexes they found using military engineers. Led by MacGregor, the Australian sappers from 3 Field Troop systematically tackled the tunnels, using telephone line and compasses to plot the subterranean passages. Small-scale contacts between the communists and the Australians continued and MacGregor was later awarded the Military Cross for his leadership.
  Originally constructed in 1945 by the Viet Minh during the fighting with the French in the First Indochina War, the tunnels at Cu Chi had taken decades to build but later had lain dormant after the war until 1960, when they were reactivated. Since then they had endured constant bombing, all the while being expanded. By 1965 they formed an underground maze of passages, fighting tunnels, meeting rooms and food caches, stretching from Saigon to the Cambodian border. Given their headquarters function, the tunnels were equipped with an array of communications and medical facilities and were defended by interlocking arcs of fire and connecting fire tunnels. Dug into hard clay which had largely protected them from American bombing, some trenches were reported as being more 1.8 metres (5.9 ft) deep, and some tunnels as long as 460 metres (500 yd), while numerous side tunnels led from the main tunnels. In places the system was between one, two and even three levels deep. The network was so extensive that they were rumoured to be able to hold 5,000 men, many of whom lived underground for up to six months at a time. On seeing the tunnels one American soldier described them at the time as "the New York subway".
  In the southern area of operations, the US 3rd Infantry Brigade was making slow progress, with the Viet Cong using hit-and-run and ambush tactics to inflict casualties on the Americans, before withdrawing into the sanctuary of their tunnels. On 9 January, the Americans located and destroyed a cache of medical supplies, a small hospital and a large amount of rice, as well as capturing 30 Viet Cong during a series of skirmishes. To the north, while 1 RAR searched the tunnel complex the American battalions of the US 173rd Airborne Brigade continued to sweep their area of operations, with a number of friendly fire incidents complicating their task. Both the US 1/503rd and US 2/503rd Battalions searched eastward toward the Saigon River and, although they continued to find supply caches and abandoned positions, they were involved in only minor skirmishes with the Viet Cong. Concealed in well-camouflaged ambush positions however, the communists inflicted a number of casualties on the Americans. Only one Viet Cong was killed during the fighting, bringing the total for the operation to just 22. Despite the large number of US troops involved they had experienced only limited contact to that point, and criticism of the operation consequently began to mount in the American media.
caption: Australian soldier in Viet Cong tunnel uncovered during Operation Crimp.
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