It was at Tobruk that the battalion fought its first major action as a complete unit in April 1941, when it undertook defensive actions during the Siege of Tobruk. During the Battle of the Salient, fought in early May, the 2/10th took over a position on the northern flank of the perimeter, relieving the &lt;a href="2/48th%20Battalion%20%28Australia%29"&gt;2/48th Battalion&lt;/a&gt;, coming under heavy air attack during the handover. After the initial German and Italian assault, on the evening of 3/4 May the 18th Brigade counter-attacked to retake positions lost; the 2/10th was given a supporting role, tasked with carrying out raids deep into the opposing forces' territory while the 2/9th and 2/12th Battalions attacked the northern and south-eastern flanks of the salient. In the fighting that followed, the 2/10th's casualties were six missing and fifteen wounded, but they inflicted heavy casualties upon their enemy before withdrawing back to the "Blue Line", about behind the main defensive line where the counter-attacking reserve forces were positioned to respond to a deep penetration.