Army Field Artillery Brigades, to be available for more flexible deployment. 1914 When the war began, British field guns (13-pounder and 18-pounder) were equipped solely with shrapnel shells, with an approximate 3:1 ratio of field guns to field howitzers (5-inch and 4.5-inch). The 18-pounder shrapnel shell contained 374 small spherical bullets. A time fuze was set to initiate the shell in the air in front of the target. This blew off the shell nose and fired the bullets forward in a cone like a shotgun – they were effective up to 300 yards from the burst. For maximum effect from the cone of bullets, the angle of descent of the shell had to be flat and not plunging. At a theoretical maximum 20 rounds per minute, it could deliver 7,480 bullets per minute at a far greater range than machine guns. The gunners and officers of Regular Army field artillery batteries were expert at closely supporting the "fire and movement" tactics of the infantry with accurate shrapnel fire. Shrapnel was effective against troops in the open, including those serving guns without gun shields. They remained effective throughout the war against opportunity targets, such as working parties. They were used for wire cutting and most importantly in the creeping barrage, where they prevented defenders from manning their trench parapets during a British assault. In this respect, they were perhaps the key element in the British artillery doctrine of neutralizing defenders during an assault instead of trying to destroy the enemy in their defences before an attack. Primacy of neutralizing defenders became the distinguishing characteristic of British artillery for the remainder of the 20th century. The first trial high-explosive TNT rounds were fired in action on 31 October 1914 by 70th Battery, 34th Brigade RFA and 54th Battery, 39th Brigade RFA on the Ypres front and were quite successful, demonstrating both that they could destroy enemy guns and kill troops. From then on, Britain increasingly supplied 18-pounders with high-explosive shells. A major lesson learned in 1914 was that the early British doctrine of positioning field guns in open or semi-open positions made them vulnerable to enemy artillery fire, and subsequently more use would be made of available sheltered and hidden positions for firing. This made the role of the Observing Officer crucial for 18-pounder batteries engaging targets as they could no longer rely on direct line of sight. These officers suffered high