The Gustav Line was a German defensive position during World War II, established in Italy in 1944. It stretched from the Tyrrhenian Sea to the Adriatic Sea, designed to slow down the advance of the Allied forces. The line included fortified bunkers, trenches, and obstacles, making it a significant challenge for the Allies. The most famous battle along the Gustav Line was the Battle of Monte Cassino, where Allied troops faced fierce resistance. The line ultimately fell to the Allies in May 1944, leading to the liberation of Rome and a shift in the war's momentum in Italy.