At first it was the custom to capture the first-line trench and to endeavour to keep it. In practice this was rarely successful. The front line of a trench system is generally lightly held; a surprise attack by determined troops can almost rely on being successful if the element of surprise is availed of. But to take a trench is one thing; to hold it another. Remember that the rest of the front line is still held by the enemy, who, working from traverse to traverse, can bomb down it. The second and third lines are also intact, with good communication trenches leading from them to the broken firing line. Bombers can also work down these communication trenches; ammunition, food and water, and (most important of all) hand-grenades, can arrive in unlimited numbers and in comparative safety. All of these things required by the attackers lodged in the enemy's trenches must come over the bullet-swept, shrapnel-torn surface of No Man's Land. By the end of a day, unless reasonable communications can be provided, the troops who so easily captured the hotly-contested position find that they must choose between annihilation or retreat. So it was raiding grew up. This appealed more to the primitive instincts of man--the sudden dash into the enemy, the attempt to achieve the maximum amount of damage in the minimum time, and to get to the home trench again before the enemy reinforcements could arrive. This method was particularly valuable when it was considered necessary to destroy the entrances to enemy galleries, to interfere with the progress of enemy saps, and to obtain prisoners for identification by the Intelligence Department. The sortie from Quinn's Post on June 4 was a typical example of the early method. If ever an attack was organized to succeed this one was. Eager volunteers from the Auckland and Canterbury Battalions were selected to carry out the work, and at 11 p.m. a heavy artillery fire was to be directed on the surrounding communication trenches. An assaulting party of sixty men was to dash across the thirty yards of No Man's Land, take the opposing trench and transpose the Turkish parapet. Two working parties were detailed to follow the first line. These men carried filled sandbags with which to build a loopholed traverse at each end of the captured trench; other parties were to commence two communication trenches from the new work to the old. The 4th Australian Infantry Brigade was held in reserve.