The Gari is a short river that flows in Monte Cassino, Italy at the southern end of the region of Lazio.

In Sant'Apollinare, few miles south of Cassino, it joins the Liri to form the Garigliano river, which marks the border between Lazio and Campania.

The Gari river (erroneously identified as the Rapido) was the site of a bloodily repulsed and ill-conceived assault during the Italian Campaign of World War II by the U.S. 36th Infantry Division, led by Major General Fred Walker from 20–22 January 1944 when the Allies were attempting to establish a bridgehead in the vicinity of Sant'Angelo in Thoedice (a frazione of Cassino) to launch attacks on the Gustav Line near Monte Cassino.

The petition read: "Be it resolved, that the men of the 36th Division Association petition the Congress of the United States to investigate the river Rapido fiasco and take the necessary steps to correct a military system that will permit an inefficient and inexperienced officer, such a General Mark W. Clark, in a high command to destroy the young manhood of this country and to prevent future soldiers being sacrificed wastefully and uselessly.

"[2] Clark was absolved of blame by the House of Representatives but never made comment on the Rapido River episode following World War II.