lifts were typically 4 minutes apart. Lifting meant that time fuzes settings had to be changed. The attackers tried to keep as close as possible (as little as 25 yards sometimes) to the bursting shrapnel so as to be on top of the enemy trenches when fire lifted beyond them, and before the enemy could get back to their parapets. Advantages While shrapnel made no impression on trenches and other earthworks, it remained the favoured weapon of the British (at least) to support their infantry assaults by suppressing the enemy infantry and preventing them from manning their trench parapets. This was called 'neutralization' and by the second half of 1915 had become the primary task of artillery supporting an attack. Shrapnel was less hazardous to the assaulting British infantry than high explosives - as long as their own shrapnel burst above or ahead of them, attackers were safe from its effects, whereas high-explosive shells bursting short are potentially lethal within 100 yards or more in any direction. Shrapnel was also useful against counter-attacks, working parties and any other troops in the open. British Expeditionary Force "GHQ Artillery Notes No. 5 Wire-cutting" was issued in June 1916. It prescribed the use of shrapnel for wirecutting, with HE used to scatter the posts and wire when cut. However, there were constraints: the best ranges for 18-pdrs were 1,800–2,400 yards. Shorter ranges meant the flat trajectories might not clear the firers' own parapets, and fuzes could not be set for less than 1,000 yards. The guns had to be overhauled by artificers and carefully calibrated. Furthermore, they needed good platforms with trail and wheels anchored with sandbags, and an observing officer had to monitor the effects on the wire continuously and make any necessary adjustments to range and fuze settings. These instructions were repeated in "GHQ Artillery Notes No. 3 Artillery in Offensive Operations", issued in February 1917 with added detail including the amount of ammunition required per yard of wire frontage. The use of shrapnel for wire-cutting was also highlighted in RA "Training Memoranda No. 2 1939". Shrapnel provided a useful "screening" effect from the smoke of the black-powder bursting charges when the British used it in "creeping barrages". Disadvantages One of the key factors that contributed to the heavy casualties sustained by the British at the Battle of the Somme was the perceived belief that shrapnel would be effective at cutting