The revolutionary Russian government led by Alexander Kerensky remained at war, attacking and pushing back the Austro-Hungarians in Galicia on 1 July. To counter this success, on 18 July after a hurricane bombardment by 136 batteries directed by Bruchmüller a "Schwerpunkt" of six German divisions from the west broke a gap in the Russian front, through which they sliced southward toward Tarnopol, thereby threatening to pocket the Russian attackers, who fled to save themselves; many of the demoralized Russian units elected committees to replace their officers. At the end of August the advancing Central Powers stopped at the frontier of Moldavia. To keep up the pressure and to seize ground he intended to keep, Hindenburg shifted north to the heavily fortified city of Riga (today in Latvia) which has the broad Dvina River as a moat. On 1 September the Eighth Army, led by Oskar von Hutier, attacked; Bruchmüller's bombardment, which included gas and smoke shells, drove the defenders from the far bank east of the city, the Germans crossed in barges and then bridged the river, immediately pressing forward to the Baltic coast, pocketing the defenders of the Riga salient. Next a joint operation with the navy seized Oesel and two smaller islands in the Gulf of Riga. The Bolshevik revolution took Russia out of the war, an armistice was signed on 16 December.