The Battle of Yalu River took place from April 30 to May 1, 1904, and was the first major land battle during the Russo-Japanese War.

It was fought near Wiju on the lower reaches of the Yalu River which divides Korea from China. The Russian Army in Manchuria, commanded by General Alexei Kuropatkin was aware that the Japanese were advancing from their forward army bases in Korea to cross the river to invade Manchura, China. Kuropatkin dispatched Lieutenant-General Zasulich with 15,000 infantry, 5,000 calvary and some 60 artillery pieces to fight a delaying action. However, these orders were ambiguous in their phrasing and were interpreted as the need to conduct the static defence of fixed positions along the Yalu.

The advancing Japanese 1st Army, commanded by Major-General Baron Tamesada Kuroik which consisted of over 40,000 men, knew from its forward scouts the exact location of the Russian positions. By dusk on April 30, the Japanese secretly crossed the Yalu in full strength which caught the Russians totally off guard. By dawn on May 1, after suffering heavy losses from overwhelming Japanese forces, the Russian troops were forced to withdraw.

The Russians suffered about 3,000 casualties during the night-long battle including about 1,400 killed in action and 600 prisoners. The Japanese losses were recorded at only 1,000 killed, wounded or missing, although it is thought that the total Japanese casualties were deliberately deflated for propaganda purposes.

The victory of a small but rising Oriental army over a European army seriously damaged Russian prestige and raised Japanese morale for further advances into Manchuria.