Vietnam War

===Collapsing U.S. morale===
{{Further|G.I. movement}}
Following the Tet Offensive and the decreasing support among the U.S. public for the war, U.S. forces began a period of morale collapse, disillusionment and disobedience.<ref name="Stewart">{{Cite book |last=Stewart |first=Richard |url=https://history.army.mil/books/AMH-V2/AMH%20V2/chapter11.htm |title=American Military History, Volume II, The United States Army in a Global Era, 1917–2003 |date=2005 |publisher=[[United States Army Center of Military History]] |isbn=978-0-16-072541-8}}</ref>{{Rp|349–350}}<ref name="Daddis">{{Cite book |last=Daddis |first=Gregory A. |title=Withdrawal: Reassessing America's Final Years in Vietnam |date=2017 |publisher=Oxford University Press |isbn=978-0-19-069110-3 |page=[{{GBurl|id=a3QzDwAAQBAJ|pg=PT172}} 172]}}</ref>{{Rp|166–175}} At home, desertion rates quadrupled from 1966 levels.<ref name="Heinl">{{Cite journal |last=Heinl |first=Robert D. Jr. |date=7 June 1971 |title=The Collapse of the Armed Forces |url=https://msuweb.montclair.edu/~furrg/Vietnam/heinl.pdf |journal=Armed Forces Journal}}</ref> Among the enlisted, only 2.5% chose infantry combat positions in 1969–1970.<ref name=Heinl/> [[Reserve Officers' Training Corps|ROTC]] enrollment decreased from 191,749 in 1966 to 72,459 by 1971,<ref>{{Cite book |last=Sevy |first=Grace |title=The American Experience in Vietnam: A Reader |date=1991 |publisher=University of Oklahoma Press |isbn=978-0-8061-2390-5 |page=[{{GBurl|id=dZg3emyCL6EC|p=172}} 172]}}</ref> and reached an all-time low of 33,220 in 1974,<ref>{{Cite news |last=Richard Halloran |date=12 August 1984 |title=R.O.T.C. Booming as Memories of Vietnam Fade |work=The New York Times |url=https://www.nytimes.com/1984/08/12/us/rotc-booming-as-memories-of-vietnam-fade.html |access-date=14 June 2018|archiveurl=https://web.archive.org/web/20230415124225/https://www.nytimes.com/1984/08/12/us/rotc-booming-as-memories-of-vietnam-fade.html|archive-date=April 15, 2023}}</ref> depriving U.S. forces of much-needed military leadership.

Open refusal to engage in patrols or carry out orders and disobedience began to emerge during this period, with one notable case of an entire company refusing orders to engage or carry out operations.<ref>{{Cite news |date=23 March 1971 |title=General Won't Punish G.I.'s for Refusing Orders |work=The New York Times |url=https://www.nytimes.com/1971/03/23/archives/general-wont-punish-gis-for-refusing-orders-53-defiant-gis-escape.html |access-date=13 June 2018|archiveurl=https://web.archive.org/web/20230409031624/https://www.nytimes.com/1971/03/23/archives/general-wont-punish-gis-for-refusing-orders-53-defiant-gis-escape.html|archive-date=April 9, 2023}}</ref> Unit cohesion began to dissipate and focused on minimizing contact with Viet Cong and PAVN.<ref name=Daddis/>{{Rp|}} A practice known as "sand-bagging" started occurring, where units ordered to go on patrol would go into the country-side, find a site out of view from superiors and rest while radioing in false coordinates and unit reports.<ref name=Ward/>{{Rp|407–411}} Drug usage increased rapidly among U.S. forces during this period, as 30% of U.S. troops regularly used marijuana,<ref name=Ward/>{{Rp|407}} while a House subcommittee found 10–15% of U.S. troops in Vietnam regularly used high-grade heroin.<ref name=Heinl/><ref name=Hastings/>{{Rp|526}} From 1969 on, search-and-destroy operations became referred to as "search and evade" or "search and avoid" operations, falsifying battle reports while avoiding guerrilla fighters.<ref>{{Cite journal |last=Robert |first=Graham |date=1984 |title=Vietnam: An Infantryman's View of Our Failure |url=https://web.viu.ca/davies/H323Vietnam/Vietnam.InfantryView.failure.pdf |journal=Military Affairs |volume=48 |issue=3 (Jul. 1984) |pages=133–139 |doi=10.2307/1987487 |jstor=1987487|archiveurl=https://web.archive.org/web/20230605173405/https://web.viu.ca/davies/H323Vietnam/Vietnam.InfantryView.failure.pdf|archive-date=June 5, 2023}}</ref> A total of 900 fragging and suspected [[fragging]] incidents were investigated, most occurring between 1969 and 1971.<ref name="Stanton">{{Cite book |last=Stanton |first=Shelby L. |title=The Rise and Fall of an American Army: U.S. Ground Forces in Vietnam, 1963–1973 |date=2007 |publisher=Random House Publishing Group |isbn=978-0-307-41734-3}}</ref>{{Rp|331}}<ref name=Ward/>{{Rp|407}} In 1969, field-performance of the U.S. Forces was characterized by lowered morale, lack of motivation, and poor leadership.<ref name=Stanton/>{{Rp|331}} The significant decline in U.S. morale was demonstrated by the [[Battle of FSB Mary Ann]] in March 1971, in which a sapper attack inflicted serious losses on the U.S. defenders.<ref name=Stanton/>{{Rp|357}} William Westmoreland, no longer in command but tasked with investigation of the failure, cited a clear dereliction of duty, lax defensive postures and lack of officers in charge as its cause.<ref name=Stanton/>{{Rp|357}}

On the collapse of U.S. morale, historian Shelby Stanton wrote:

{{Blockquote|In the last years of the Army's retreat, its remaining forces were relegated to static security. The American Army's decline was readily apparent in this final stage. Racial incidents, drug abuse, combat disobedience, and crime reflected growing idleness, resentment, and frustration{{Nbsp}}... the fatal handicaps of faulty campaign strategy, incomplete wartime preparation, and the tardy, superficial attempts at Vietnamization. An entire American army was sacrificed on the battlefield of Vietnam.<ref name=Stanton/>{{Rp|366–368}}}}