As 1914 staggered to its bloody conclusion, the “Great War” dissolved into a horrific grind along the 500 battle-scarred miles of the Western Front. Britain and France had suffered nearly a million casualties in the war’s first four months alone, and the deadly stalemate in the trenches increasingly frustrated Britain’s 40-year-old First Lord of the Admiralty who asked the prime minister, “Are there not other alternatives than sending our armies to chew barbed wire in Flanders?” That rising star of British politics, Winston Churchill, believed he had the solution for breaking the impasse—a second front.

Although the political head of the Royal Navy, the ambitious Churchill also fancied himself a military strategist. “I have it in me to be a successful soldier. I can visualize great movements and combinations,” he confided in a friend. The young minister proposed a bold stroke that would win the war. Abandoning his earlier plan to invade Germany from the Baltic Sea to the north, he now championed another proposal under consideration by the military to strike more than 1,000 miles to east. He proposed to thread his naval fleet through the needle of the Dardanelles, the narrow 38-mile strait that severed Europe and Asia in northwest Turkey, to seize Constantinople and gain control of the strategic waterways linking the Black Sea in the east to the Mediterranean Sea in the west. Churchill believed the invasion would give the British a clear sea route to their ally Russia and knock the fading Ottoman Empire, the “sick man of Europe” that had reluctantly joined the Central Powers in October 1914, out of the war, which would persuade one or all of the neutral states of Greece, Bulgaria and Romania to join the Allies.

Britain’s war cabinet backed the plan, which had been under consideration even before the Ottoman Empire joined the war. The first step would be an attack on the Gallipoli Peninsula on the northern side of the Dardanelles, an operation that Churchill, who now became the plan’s chief advocate, knew would be risky. “The price to be paid in taking Gallipoli would no doubt be heavy,” he wrote, “but there would be no more war with Turkey. A good army of 50,000 and sea-power—that is the end of the Turkish menace.”

The British War Office, however, refused to send as many troops as he wished, but Churchill sent in the fleet anyway. The attack on Gallipoli began on the morning of February 19, 1915, with long-range bombardment of the peninsula by British and French battleships. Despite initial success, the attack stalled as the weather grew worse and Allied minesweepers drew heavy fire. Under pressure from Churchill to continue the attack, the British naval commander in the region, Admiral Sackville Carden, suffered a nervous collapse and was replaced by Vice-Admiral John de Robeck. Days later on the morning of March 18, British and French battleships entered the straits and launched an attack. Again, the Allies had the upper hand in the initial hours until undetected mines sank three ships and severely damaged three others. With half of his fleet out of commission, de Robeck ordered a withdrawal. Churchill wanted his commander to press on, but de Robeck wanted to wait for army support forces, which were now being provided after all. As the fleet hesitated, it lost the advantage.

In the wake of the failed naval attack, the Allies launched a major land invasion of Gallipoli on April 25. The month-long delay allowed the Turks to rush reinforcements to the peninsula and boost their defenses, and the British, French and members of the Australian and New Zealand Army Corps (ANZAC) could make little progress from their beachheads. The turquoise waters of the Aegean Sea turned crimson as the stiff Turkish resistance struck down the waves of Allied forces that washed ashore. The Battle of Gallipoli became a slaughter and quickly morphed into a stalemate just as bloody, just as pointless as that on the Western Front. In the first month after storming the peninsula, the Allies lost 45,000 men. The ill-fated Gallipoli Campaign lasted nine months before the evacuation of the last Allied troops in January 1916. Each side sustained 250,000 casualties with 46,000 Allied troops and 65,000 Turkish troops dead.

The invasion had been scuttled by incompetence and hesitancy by military commanders, but, fairly or unfairly, Churchill was the scapegoat. The Gallipoli disaster threw the government into crisis, and the Liberal prime minister was forced to bring the opposition Conservatives into a coalition government. As part of their agreement to share power, the Conservatives wanted Churchill, a renegade politician who had bolted their party a decade earlier, out from the Admiralty. In May 1915, Churchill was demoted to an obscure cabinet post.

“I am the victim of a political intrigue,” he lamented to a friend. “I am finished!” Displaying the steely determination that would serve him well in World War II, however, the marginalized Churchill did not slink from the fight. In November 1915, the statesman turned soldier. Churchill resigned from the government, picked up a gun and headed to the front lines in France as an infantry officer with the Royal Scots Fusiliers. After several brushes with death, he returned to politics in 1917 as the munitions minister in a new coalition government headed by Liberal Prime Minister David Lloyd George.

Churchill, however, remained haunted by Gallipoli for decades. “Remember the Dardanelles,” his political opponents taunted when he stood up to speak in the House of Commons. When running for Parliament in 1923, hecklers called out, “What about the Dardanelles?” The “British Bulldog” embraced Gallipoli as a brilliant failure. “The Dardanelles might have saved millions of lives. Don’t imagine I am running away from the Dardanelles. I glory in it,” he responded.

Although many shared the views of a political insider who in 1931 speculated that “the ghosts of Gallipoli will always rise up to damn him anew,” Churchill became prime minister in 1940 with Britain once again embroiled in war. Upon taking office, he wrote, “All my past life had been a preparation for this hour and for this trial.” That included Gallipoli.