objective of the advance these columns would deploy into line, and each unit would entrench itself on the new position. As it is essential for success that _direction_ should be maintained and _connection_ preserved, the ground over which the advance is to be made must be {148} examined beforehand and landmarks noted, and touch must be kept by means of ropes or any available device. Care must also be taken in consolidating the position that the entrenchments have a general alignment towards the enemy and that they are so sited as to protect from enfilade fire. Night Assaults.--Night Assaults are delivered by troops already deployed into attack formation. It is an established tactical principle that "when the conditions of the fire-fight are likely to be favourable, it is probably better to accept the inevitable casualties that must result from a struggle for fire supremacy, rather than adopt the undoubted hazards of a night assault." These conditions are frequently so unfavourable in Position Warfare, owing to the strength of consolidated positions and to the increasing accuracy and density of artillery fire, that assaults are made of necessity in the hours of darkness, in preference to those of daylight. During the _Battle of the Somme_ (July 1-17, 1916) a night advance was made by seven divisions on a front of about 4 miles. The troops moved out in the early hours of July 14, for a distance of about 1,400 yards, and lined up in the darkness below a crest some 300 to 500 yards from the enemy's trenches. Their advance was covered by strong patrols and their correct deployment had been ensured by white tapes laid out on the ground earlier in the night of July 13-14. The whole movement was carried out unobserved and without touch being lost in any case. The assault was delivered at 3.25 a.m., when there was just sufficient light to be able to distinguish friend from foe at short range, and along the whole front attacked the troops were preceded by an effective artillery barrage. They swept over the enemy's first-line trenches and consolidated their position in the defences beyond.