The Battle of Kursk saw a clash between German and Soviet ground forces resulting in the largest tank battle of the entire war, involving over 6,000 tanks. The Germans had recently received hundreds of new Tiger heavy tanks and the newly developed Panther tank, which suffered from high rates of technical failure during the battle. The Germans intended the offensive against the Kursk salient to be a display of strength that would help turn the tide against the advancing Soviets; however, the Soviets had gained knowledge of many details of the upcoming German attack thanks to interceptions of German communications by British intelligence. This allowed them to prepare deep defensive networks with many layers of fortifications and over 1.3 million troops. After the Germans launched Operation Citadel on 5 July they broke through the first line of Soviet defence but were soon held up by the Soviet defence-in-depth strategy and ferocious counterattacks.