Final answer:
Winston Churchill resigned from his post as First Lord of the Admiralty due to the Gallipoli Campaign's failure. He later served on the Western Front and made a political comeback that eventually led to his role as Prime Minister during WWII. Gallipoli also significantly impacted the national identities of Australia and New Zealand and marked the rise of Mustafa Kemal in Turkey.
Step-by-step explanation:
After the failure of the Gallipoli Campaign, Winston Churchill was compelled to resign from his position as First Lord of the Admiralty. The Gallipoli Campaign, envisioned by Churchill to create a new front and alleviate pressure on the Allied forces, turned into a catastrophic defeat with immense losses for the Allies. The ill-fated Gallipoli invasion basically grounded to a halt the political ascent of Churchill, who had overseen the organization and execution of the campaign.
Despite the initial setbacks following Gallipoli, Churchill did not leave the political scene for long. After resigning, Churchill re-enlisted in the British Army and served on the Western Front for a period of time. His reputation began to recover as he went on to hold a number of significant government positions in the subsequent years, leading to his eventual rise as the Prime Minister during the Second World War. His leadership during WWII erased much of the stigma associated with the Gallipoli debacle.
The Gallipoli Campaign also had profound effects on the nations involved, particularly Australia and New Zealand, where ANZAC Day is commemorated. On the other hand, for the Ottoman Empire, the campaign solidified the reputation of General Mustafa Kemal (later Atatürk), paving the way for the foundation of the modern Turkish Republic.