attack of any great size on the south bank had been considered impossible by the German command and after the 10th Bavarian Division was transferred north of the river to reinforce the XIV Reserve Corps, divisional frontages were made even wider on the south side of the river, the three remaining divisions of XVII Corps using their third regiment to fill the gap at the cost of having no reserve. The French preliminary bombardment caused the Germans many casualties and destroyed many machine-guns and mortars. When the attack began, concealed by mist, the German defenders were surprised and overrun. The French artillery had batteries per of front, balloons were opposite the German 11th Division alone and French artillery observation aircraft were flown so low by their pilots over Estrées that German soldiers could see the faces of the crews. The division had only two field artillery regiments and part of one regiment sent as reinforcement, with no heavy guns for counter-battery fire, except for periodic support from a small number of heavy guns covering all of the south side of the river. The German artillery group around Estrées, Soyécourt and Fay attempted a systematic bombardment of the French front line on 30 June. The French replied with shells on one German field regiment alone, which knocked out three guns. By the time of the attack of 1 July, German artillery on the south bank had been hit by and had almost been silenced by Only eight heavy batteries were available to the Germans on the south bank; at the French barrage lifted off the German front line and three mines were blown under a redoubt at the village of Fay. A measure of surprise was gained, despite losses to German flanking fire from beyond the southern flank of the attack. Grenadier Regiment 10 had been subjected to a "torrent" of fire overnight, which had forced the German infantry to shelter in mine galleries. A gas bombardment was synchronised with the French infantry attack and the mine explosions at killed many of the sheltering troops. By the German defences had been overwhelmed and the garrisons killed or captured; such reinforcements as existed were moved forward to occupy the second position south of Assevillers. I Colonial Corps On the south bank, the I Colonial Corps (2nd, 3rd, 16th Colonial and the 99th Territorial divisions along with ) also attacked two hours after