the tactical successes of the southern shock group. Timoshenko was unable to choose a point of main effort for his advancing troops, preferring a broad-front approach instead. The Germans traded space for time, which suited their intentions well. 1st Panzer Army counterattacks On 17 May, supported by Fliegerkorps IV, the German army took the initiative, as Kleist's 3rd Panzer Corps and 44th Army Corps began a counterattack on the Barvenkovo bridgehead from the area of Aleksandrovka in the south. Aided greatly by air support, Kleist was able to crush Soviet positions and advanced up to ten kilometres in the first day of the attack. Soviet troop and supply convoys were easy targets for ferocious Luftwaffe attacks, possessing few anti-aircraft guns and having left their rail-heads 100 kilometres to the rear. German reconnaissance aircraft monitored enemy movements, directed attack aircraft to Soviet positions and corrected German artillery fire. The response time of the 4th Air Corps to calls for air strikes was excellent, only 20 minutes. Many of the Soviet units were sent to the rear that night to be refitted, while others were moved forward to reinforce tenuous positions across the front. That same day, Timoshenko reported the move to Moscow and asked for reinforcements and described the day's failures. Vasilevsky's attempts to gain approval for a general withdrawal were rejected by Stalin. On 18 May, the situation worsened and Stavka suggested once more stopping the offensive and ordered the 9th Army to break out of the salient. Timoshenko and Khrushchev claimed that the danger coming from the Wehrmacht's Kramatorsk group was exaggerated, and Stalin refused the withdrawal again. The consequences of losing the air battle were also apparent. On 18 May the Fliegerkorps IV destroyed 130 tanks and 500 motor vehicles, while adding another 29 tanks destroyed on 19 May. On 19 May, Paulus, on orders from Bock, began a general offensive from the area of Merefa in the north of the bulge in an attempt to encircle the remaining Soviet forces in the Izium salient. Only then did Stalin authorise Zhukov to stop the offensive and fend off German flanking forces. However, it was already too late. Quickly, the Germans achieved considerable success against Soviet defensive positions. The 20 May saw more of the same, with the German forces closing in from the rear. More German divisions were committed to the battle that day, shattering several Soviet counterparts,