The Gari is a short river that flows in Cassino, Italy at the southern end of the region of Lazio. Along its banks, in 1944, occurred the Battle of Gari River, one of the most bloody battle of the Italian Campaign of World War II in 1944, best known as Battle of the Rapido River.

The river origins from a spring in the center of Cassino, in Piazza Corte, at the foot of Montecassino. It flows undergroung and reappear in the Villa Comunale, the main public park in the town. In the thermal area known as Varronian Thermal Baths, it increases considerably its discharge from several springs, as well as from the Rapido River. 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 battle

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 assault was opposed by two battalions from the German 15th Panzer Grenadier Division under General-Lieutenant Rudolf Sperl. American troops suffered over 2,000 casualties in the failed assault.