their defenders from the first line of trenches just before the Soviet artillery would have obliterated them. Whereas according to a report to Stalin, Zhukov wrote that: Considering that the enemy moves its infantry from the first to the second and third lines of trenches in the morning, I used a nightly artillery barrage with a high density of fire for 30 minutes, with the use of searchlights to blind the enemy and light up the terrain ahead of the advancing troops... According to the interrogated prisoners, artillery fire was so sudden and overwhelming that the enemy did not have time to move from the first trench line; the second and third lines were at all times under heavy fire from our artillery. As a result of this, the enemy units in the first line of defence suffered heavy casualties. The swampy ground proved to be a great hindrance, and a German counter-barrage caused heavy Soviet casualties. Frustrated by the slow advance, Zhukov threw in his reserves, which according to his earlier plan were to be held back until the expected breakthrough. By early evening, an advance of had been achieved (the 7th Rifle Corps from the 3rd Shock Army had advanced ), but the second German defensive line remained intact. Zhukov was forced to report that his battle was not going as planned. However, in the south the attack by Konev's 1st Ukrainian Front was going according to plan. To spur Zhukov on, Stalin told him that he had let Konev direct his tank armies north towards Berlin. On the second day, the 1st Belorussian Front's troops continued to advance in accordance with the initial plan. By nightfall on 17 April, the German second defensive line (Stein Stellung) was broken by the 5th Shock Army and 2nd Guards Tank Army. The right flank of the 4th Guards Rifle Corps of the 8th Guards Army, together with the 11th Guards Tank Corps of the 1st Guards Tank Army, had taken advantage of the success of their comrades and also advanced. The 47th and the 3rd shock armies progressed another . To the south however, the 1st Ukrainian Front was pushing back the 4th Panzer Army; the left flank of Army Group Centre under Ferdinand Schörner was beginning to crumble. Schörner kept his two reserve panzer divisions in the south covering his centre, instead of using them to shore up the