On 21 March 1918, the Germans attempted a breakout through the Michael Offensive, which was part of the much larger German spring offensive; the AIF suffered 15,000 casualties due to this effort. During this operation, Australian troops conducted a series of local defences and offensives to hold and retake Villers–Brettoneux over the period 4 to 25 April 1918. After the cessation of offensives by the German Army, the Australian Corps began participating in "Peaceful penetration" operations, which were localised raids designed to harass and gain small tracts of territory; these proved so effective that several major operational objectives were captured.