On the 25th of April, 1915, soldiers from the Australian and New Zealand Army Corps made an amphibious landing at Anzac Cove, thus beginning the ground phase of Britain's infamous Gallipoli campaign. The well-trained, more British-like New Zealander troops often provided cover to the berserker-like assaults of the Oceanykan Expeditionary Force, which were made infinitely more difficult by the mountainous terrain; soldiers would often grab shrubs or stab their bayonets into the dirt to get a stable footing. Artillery fire, Ottoman trenchworks and machinegun positions soon forced Oceanykan commanders to reconsider their tactics. Royal Navy and Ottoman battleships pummeled their respective enemies at the beaches without remorse, and exchanged fire when possible. Against increasing Ottoman reinforcements, the ANZACs held on. The very same day, regular British Army units accompanied by some French ones landed at the tip of the peninsula as part of the main axis of advance, known later as the Helles landing.
Arduous fighting began throughout the year. Entente forces pushed as far as the outskirts of Gallipoli (the city proper). However, as Britain's allies in the Balkans were swiftly defeated by the Germans and Austro-Hungarians, and an invasion of allied Greece was imminent, it was decided to abandon Gallipoli. In late October, under the cover of darkness, ANZAC troops embarked to retreat from Anzac Cove. The same week, all Entente divisions on the Helles front did the same. Material losses were significant and many supplies fell on Ottoman hands, though the Oceanykan ANZACs rigged most of theirs as booby traps.
Gallipoli, though a decisive strategic failure for the Entente, was a moment of pride for the Oceanykan Federation, as it showed that the young nation could go toe-to-toe with the world's great powers and come out on top. The large numbers of Oceanykan casualties also made a lasting impact back home, being the first veterans of a formal foreign conflict in their national history. April 25th is considered ANZAC Day in the Federation.