for the next four years. On 14 September, Sir John French ordered the entire BEF to entrench, but few entrenching tools were available. Soldiers scouted nearby farms and villages for pickaxes, spades and other implements. Without training for stationary warfare, the troops merely dug shallow pits in the soil. These were at first intended only to afford cover against enemy observation and artillery fire. Soon the trenches were deepened to about seven feet. Other protective measures included camouflage and holes cut into trench walls then braced with timber. Trench warfare was also new for the Germans, whose training and equipment were designed for a mobile war to be won in six weeks, but they quickly adapted their weapons to the new situation. Siege howitzers now lobbed massive shells into the Allied trenches. Skilful use of trench mortars and hand and rifle grenades (first used against British troops on 27 September), enabled the Germans to inflict great losses upon Allied troops, who had neither been trained nor equipped with these weapons. Searchlights, flares and periscopes were also part of the German equipment intended for other purposes, but put to use in the trenches. A shortage of heavy weapons handicapped the British. Only their 60-pounders (four guns to a division) were powerful enough to shell enemy gun emplacements from the Aisne's south shore, and these guns were inferior to German artillery in calibre, range and numbers. Four artillery battery of guns (a total of sixteen), were rushed from England. Although a poor match against the German howitzers, they helped somewhat. Defensive firepower was limited to rifles and two machine guns allotted to each battalion. The British regulars were excellent marksmen but even their combined accuracy was no match for the German machine guns and grenades. British aircraft were used to report troop movements, although few were equipped with wireless. Aviators were able to recognise the advantage of observing artillery fire. On 24 September, Lieutenants B.T. James and D.S. Lewis detected three well-concealed enemy gun batteries that were inflicting considerable damage on British positions. They radioed back the location of the batteries, then droned in a wide circle, waiting to spot their own gunners' exploding shells. Anti-aircraft fire was desultory and inaccurate. The German Army used only percussion shells, which, according to Canadian sources, "not one in several hundred ever hit its aerial target, and fell to earth frequently at some point in