In the early hours of 16 April, the offensive began with a massive bombardment by thousands of artillery pieces and Katyushas. Well before dawn, the 1st Belorussian Front attacked across the Oder and the 1st Ukrainian Front attacked across the Neisse. The 1st Belorussian Front was the stronger force, but it had the more difficult assignment since it was facing the bulk of the German forces.
The assault by the 1st Belorussian Front started with an intense artillery bombardment. According to Beevor and Ziemke, Heinrici and Busse had anticipated the attack and withdrew their defenders from the first line of trenches just before the Soviet artillery would have obliterated them. However, this is contradicted by a report to Stalin, in which Zhukov writes 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 defense 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 4–6 km (2.5–3.7 mi) had been achieved (the 77th Rifle Corps from the 3rd Shock Army had advanced 8 km (5.0 mi)), 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 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 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 4–8 km (2.5–5.0 mi).
To the south however, the 1st Ukrainian Front was pushing back the 4th Panzer Army; the left flank of Army Group Center under Ferdinand Schörner was beginning to crumble. Schörner kept his two reserve panzer divisions in the south covering his center, instead of using them to shore up the 4th Panzer Army. This was the turning point in the Berlin Offensive, because the positions of both Army Group Vistula and the center and right sectors of Army Group Center were becoming untenable. Unless they fell back in line with the 4th Panzer Army, they faced envelopment. In effect, Konev's successful attack on Schörner's relatively poor defenses to the south of Seelow Heights was unhinging Heinrici's defense....
Gen. Heinrici had said before the battle that the Seelow Heights could be held for only three or four days without reinforcements, which he did not have. From 19 April, the road to Berlin—90 km (56 mi) to the west—lay open. By 23 April, Berlin was fully encircled and the Battle of Berlin entered its last stage. Within two weeks, Adolf Hitler was dead and the war in Europe was effectively over. As a result of the 1st Belorussian Front's success at the Seelow Heights and the Order Front in general, most of the forces of the German 9th Army were encircled before they could retreat to Berlin. The city was then defended by broken formations, the Volkssturm, police and air defense units, which allowed the Soviet Army to take it in only 10 days.
After the war, Zhukov's critics asserted that he should have stopped the 1st Belorussian Front's attack via the direct line to Berlin along the autobahn and instead made use of the 1st Ukrainian Front's breakthrough over the Neisse or concentrate its armies on surrounding Berlin from the north. This would have bypassed the strong German defenses at Seelow Heights, and avoided many casualties and the delay in the Berlin advance. Zhukov supposedly took the shortest path, so that his troops would be the first ones to enter the city.... In actuality only two of the five armies of the 1st Belorussian Front attacked the Seelow Heights themselves and the heights were eventually bypassed from the north as soon as there was a narrow breakthrough.... According to Russian historian Aleksey Isaev, based on archival data the 1st Belorussian Front lost 20,000 men, including 5,000-6,000 killed and missing, which "makes up a smaller part of the Berlin Operation as a whole, and the losses of the 1st Belorussian Front in that operation," and so it is incorrect to think that the heights were "soaked with blood and covered with corpses."