With the War in Afghanistan now past its 16th anniversary (the initial U.S.-led invasion began Oct. 7, 2001) it is now the longest war in American history (The Vietnam War can claim a piece of that, but more on that controversy later). While the initial war goals of overthrowing the Taliban and chasing out al-Qaida seemed to be accomplished early on in the war, the Taliban is now in possession of more territory now than at any time since 2001( ᔥNew York Times ).
American forces have now been fighting in Afghanistan for 192 months. As the chart below shows, that exceeds the length of time American troops fought against Filipino and Moro forces in the Philippine-American War (1899-1901) and the Moro Wars (1899-1913). The Moro Wars, interestingly enough, were fought against Muslim inhabitants of the southern Philippine Islands in jungle warfare similar to what American (and, earlier, the French) experienced in Vietnam.
And speaking of Vietnam, while the chart below has that war beginning in 1964 with the Gulf of Tonkin Incident and the subsequent Congressional resolution authorizing major combat, the argument can be made America’s war in Vietnam in fact spanned 20 years, if we start it as the first American casualty in that country in 1955 and end it with the Fall of Saigon and the Mayaguez Operation in 1975. ↬Historyguy.com
With no clear end in sight, it is likely that America’s combat role in Afghanistan will continue, and this conflict’s title as longest American war will stand for quite some time.