German infantry began to avoid trench lines in mid-July and occupied shell-holes, which made Allied bombardments less effective and diverted infantry into mopping-up operations. Allied attacks on limited objectives reduced the effectiveness of German defensive dispersal, positions were incessantly bombarded, trenches, barbed wire and dugouts disappearing as far back as the second line. Shell-hole positions about apart, containing two or three men were quickly overrun by Anglo-French infantry and prepared for defence, before a could be made. Deliberate counter-attacks were planned but most were cancelled due to shortages of troops, artillery and ammunition. Attempts to connect shell-hole positions during quiet periods failed, as Allied air reconnaissance quickly directed artillery-fire onto them. Trenches were evacuated before attacks, which began the development of defended areas, in which small groups manoeuvred to deprive Allied gunners of recognisable targets, vastly inflating the amount of ammunition necessary for bombardments.