main German strong-points, as smaller guns pulverised the villages close to the front line, from which civilians were hurriedly removed. German troops billeted in the villages moved into the open to avoid the shelling and on heavy rain added to the devastation, as the bombardment varied from steady accurate shelling to shell-storms and periods of quiet. At night British patrols moved into no man's land and prisoners captured by the Germans said that they were checking on the damage and searching for German survivors. German interrogators gleaned information suggesting that an offensive would come either side of the Somme and Ancre rivers at on 29 June. All of the German infantry stood to with reinforcements but the bombardment resumed in the afternoon, rising to drumfire several times. Artillery-fire concentrated on small parts of the front, then lines of shells moved forward into the depth of the German defences. Periodic gas discharges and infantry probes continued but German sentries watching through periscopes were often able to warn the garrisons in time to react. The bombardment on 30 June repeated the pattern of the earlier days, by when much of the German surface defences had been swept away, look-out shelters and observation posts were in ruins and many communication trenches had disappeared. On the night of the bombardment fell on rear defences and communication trenches, then at dawn British aircraft "filled the sky", captive balloons rose into the air at and an unprecedented barrage began all along the German front, until when the bombardment abruptly stopped. The remaining German trench garrisons began to leave their shelters and set up machine-guns in the remains of trenches and shell-holes, which proved difficult to spot and allowed the occupants to change direction, easily to face threats from all directions. Where the British infantry advanced close behind the barrage the German defenders were often overrun and at Montauban, Mametz and around Fricourt, the Germans were rushed, while most were still underground. Further north, the Germans had time to emerge and stopped most attacks in no man's land. In the 26th Reserve Division area, a front of from Ovillers to Serre, four regiments occupied the first line with two battalions each, one in the support line and one in reserve. The Germans emerged to see lines of British infantry in no man's land and opened rapid fire on them, lines and waves falling down, reforming and moving