On June 10, 1190, during the Third Crusade, Holy Roman Emperor Frederick I, Barbarossa drowned while crossing the Saleph River leading an army to Jerusalem. An excerpt from the article:
"Third Crusade
Though Barbarossa had reconciled with the pope, he continued to take actions to strengthen his position in Italy. In 1183, he signed a treaty with the Lombard League, separating them from the pope. Also, his son Henry married Constance, the Norman princess of Sicily, and was proclaimed King of Italy in 1186. While these maneuvers led to increased tension with Rome, it did not prevent Barbarossa answering the call for the Third Crusade in 1189.
Death
Working in conjunction with Richard I of England and Philip II of France, Barbarossa formed an immense army with the goal of retaking Jerusalem from Saladin. While the English and French kings traveled by sea to the Holy Land with their forces, Barbarossa's army was too large and was forced to march overland. Moving through Hungary, Serbia, and the Byzantine Empire, they crossed the Bosporus into Anatolia. After fighting two battles, they arrived at the Saleph River in southeast Anatolia. While stories vary, it is known that Barbarossa died on June 10, 1190, while jumping into or crossing the river. His death led to chaos within the army and only a small fraction of the original force, led by his son Frederick VI of Swabia, reached Acre.
Legacy
Over the centuries following his death, Barbarossa became a symbol for German unity. During the 14th century, there was a belief that he would rise from the imperial castle of Kyffhäuser. During World War II, the Germans launched a massive attack against Russia, which they dubbed Operation Barbarossa in honor of the medieval emperor."