At 03:00 in the morning on 16 April 1945, the 1st Belorussian Front under command of Marshal Georgy Zhukov began to attack the German positions. The German 9th Army under General Theodor Busse was positioned in the Oder Marsh, about 90 km east from Berlin. Because the German troops seemed to offer little resistance, Zhukov launched an attack which, however, met with little success. The 143 antiaircraft defence searchlights placed in the front lines in order to blind the enemy, caused disorientation among his own troops instead. The intensity of German defensive fire took the Soviet troops by surprise. Earlier than planned, Zhukov committed two armored corps to the battle, causing chaos beyond the Küstrin (Kostrzyn) bridgehead, where the tanks were backed up. The German units, by contrast, were able to launch several successful counter-blows against enemy armor. As the first Soviet tanks reached the Seelow Heights, and tried to work their way up, it rapidly became clear that Zhukov had underestimated how high the heights really were. In some places, the incline was so steep that the commanders had to search for detours, and in doing so, often ran up against German defensive positions. Fierce fighting ensued in the Oder Marsh and the Seelow Heights. The tide did not turn until 18 April. On Highway 1 just past Seelow, Soviet tanks reached the highway at Diedersdorf and began to push forward toward Müncheberg. Finally on 19 April, Zhukov’s troops broke through the last line of defense and began to advance towards Berlin, counting tens of thousands killed or injured on both sides.