At the beginning of the First World War, Ivanov was appointed commander-in-chief of the Southwestern Front. At first, he together with the aged general von Saltza suffered a minor defeat at Kraśnik, but success came next when the Russians successfully advanced into Austrian Galicia, with the Russian casualties of about 200,000, the Austrians having roughly twice the casualties, including thousands of POWs. For the huge successes at the front, he was awarded the Order of St. Vladimir, 1st class with swords, and the Order of St, George of the 2nd degree, being three of the only generals that were awarded this high decoration, the other two generals being General Nikolai Ruzsky and Nikolai Yudenich. During the battle at the Vistula River, he with his Southwestern Front armies (4th Army and the 9th Army), together with the Northwestern Front commander-in-chief General Ruzsky with his armies (2nd Army and the 5th Army) from the North. In the matter of a month, General Ivanov and General Ruzsky's troops successfully repulsed the German advance, taking about a hundred kilometres of land. Later on, General Ivanov commanded an operation towards Kraków, it was successful at first, but was later ordered to retreat, ending the initial success.