This rendered possible another threat to the Red Army—one from Gen. Yudenich, who had spent the summer organizing the Northwestern Army in Estonia with local and British support. In October 1919 he tried to capture Petrograd in a sudden assault with a force of around 20,000 men. The attack was well-executed, using night attacks and lightning cavalry maneuvers to turn the flanks of the defending Red Army. Yudenich also had six British tanks, which caused panic whenever they appeared. The Allies gave large quantities of aid to Yudenich, who, however, complained that he was receiving insufficient support.