As part of an endeavour to defeat the Ottoman Empire and force a supply route through to Russia via the Bosporus and the Black Sea, the British War Council formulated a plan to invade the Gallipoli Peninsula. On 25 April 1915, the men of the 1st Australian Brigade—of which the 1st Battalion was part—landed at Anzac Cove between 05:30 and 07:30 among the second and third waves of Australian troops. The 1st Battalion was meant to be held in reserve, but due to heavy casualties and confusion the unit soon went into action. Following a request for reinforcements, Shout moved up with one of the 1st Battalion's companies to the hill feature Baby 700. Arriving at the position around 11:00, he led a party to hold the rear left flank of the hill as part of the Australians' rearguard action. The Australian position on Baby 700 had become dire by that afternoon, a situation compounded by the small number of available infantry in the area and the complete lack of artillery support, when the Turkish forces launched a counter-assault. By this time, Shout and Lieutenant Leslie Morshead of the 2nd Battalion were the only two surviving officers in their sector of the line. At 16:30, the Turks broke through the defensive line and the Australians were forced to abandon their position on the hill. Shout was one of the last to evacuate, and withdrew down towards the beach. During his retreat, Shout encountered Lieutenant Colonel George Braund, commanding officer of the 2nd Battalion, on Walker's Ridge. Braund dispatched Shout to the beach with a request for reinforcements. Shout duly relayed the message, and was immediately tasked with leading 200 stray men to reinforce the thin defensive line near Braund's position. Shout established a post at the base of the ridge as dusk began to fall, and his men started to dig in.
By 27 April, Shout had been continually in action without rest since the landing. That morning, he was sent to Walker's Ridge to replace a wounded officer in a vulnerable sector of the line. As the Turks occupied positions in the scrub just beyond the Australians' trench, Shout and his men were subjected to accurate and heavy rifle fire throughout the day. Accordingly, Shout reorganised his men and, exposing himself to the Turks' fire, ventured out to reconnoitre the enemy's position. He was then able to accurately direct the rifle fire of his men. Though wounded early in the action, Shout refused to leave the frontline. As the fighting wore on, the Turks closed in on the Australian trench and Shout led a bayonet charge to hold them at bay. He was later wounded a second time, a bullet passing through his arm and rendering it useless. Still, he refused to leave. Soon after, he was wounded a third time and evacuated for medical treatment. During the engagement, Shout had carried several wounded men away from the frontline. Cited for his "conspicuous courage and ability" at Walker's Ridge, Shout was awarded the Military Cross, becoming the first member of his battalion to receive the decoration.