1. The Allies wildly underestimated their enemies.

Long called the “sick man of Europe,” the Ottoman Empire had suffered one military defeat after another in the lead-up to World War I. Its reputation was so bad, in fact, that the British and their main allies, the French, half-thought they would cause the government to collapse simply by showing up. With their modern battleships busy fighting Germany, they almost exclusively employed outdated models during the Gallipoli campaign. They also made little effort to gather intelligence on the opposing Ottoman force. Lacking adequate maps, the steep gully-filled terrain caught them by surprise. And to top it off, most of their troops were inexperienced.

Graphic map of the Dardenelles.

2. The Allies hoped to win with their navy alone.

Believing that victory could be achieved without the use of the army, the British and French opened up the Gallipoli campaign on February 19, 1915, with a long-range naval bombardment. After a bad weather delay of nearly a week, they then knocked out the forts at the mouth of the Dardanelles, the narrow strait separating Europe from Asia that served as the gateway to Constantinople. The next step involved sending minesweepers into the strait to clear the way forward; however, steady howitzer fire from shore prevented them from effectively doing their job. Since big warships could not shoot accurately enough, and marine landing parties faced stiff resistance, all attempts to silence these howitzers failed. Yet Allied leaders back home enjoined their military commanders to press ahead anyway, and on March 18 they attempted to power their way through the strait with 18 battleships, along with cruisers, destroyers and numerous other support vessels. Sure enough, mines and shellfire sank three of these battleships and severely damaged three others, forcing a retreat. Days later, it was decided that army troops would be needed after all.

3. The Allies never made it much past the beach.

The ground attack began on April 25, when Allied soldiers landed simultaneously at various points near the mouth of the Dardanelles. British troops carved out a foothold at Cape Helles, the southernmost point of the Gallipoli Peninsula, located on the European side of the strait, and were soon reinforced by the French. But despite several bloody battles, they never managed to advance more than a few miles inland. Not far to the north on the Gallipoli Peninsula, the Australian and New Zealand Army Corps established an even more tenuous foothold, having been stopped in its tracks by future Turkish President Mustafa Kemal Atatürk, then a divisional commander. With both bridgeheads devolving into trench warfare similar to that on the Western Front, the Allies launched a new amphibious assault in early August. This only succeeded, however, at forming a third static foothold.

Turkish troops on parade, 1915. (Credit: FPG/Hulton Archives/Getty Images)

4. One of the few things that went well for the Allies was the withdrawal.

Historians often criticize the Allied generals for acting incompetently throughout the Gallipoli campaign. Yet they did get one thing right. As they gradually evacuated the peninsula in December 1915 and January 1916, they ordered the troops to bring in empty supply boxes, leave up extra tents, light extra cooking fires, continue firing artillery and even put helmets on sticks to exaggerate their numbers. Such trickery helped prevent the Ottomans from understanding exactly what was happening until it was too late to press their advantage. During the entire evacuation process, they inflicted virtually no casualties—much to the pleasant astonishment of the Allied force’s newly installed top commander, who had estimated losses of 30-40 percent.

5. Submarines played a major role in the campaign.

Though Allied troops and surface boats struggled to make any progress at Gallipoli, several submarines succeeded in sneaking through the Dardanelles and into the waters around Constantinople. Attacking merchant vessels, warships and troop transports alike, they largely prevented the terrified Ottomans from moving men and supplies by sea. One particularly daring British submarine commander, Martin Nasmith, destroyed more than 80 enemy craft. He once even fired at soldiers along the shore and landed a saboteur to blow up a railway bridge. The Germans likewise had submarines operating in the area, including one U-boat that sank two British battleships in the span of 48 hours. Meanwhile, up in the sky, British seaplanes made history with the first-ever aerial torpedo attacks.

British troops advancing at Gallipoli, August 1915. (Credit: Hulton Archive/Getty Images)

6. Gallipoli almost derailed Winston Churchill’s career.

As Britain’s powerful First Lord of the Admiralty, Winston Churchill masterminded the Gallipoli campaign and served as its chief public advocate. It was no surprise then that he ultimately took much of the blame for its failure. Demoted in May 1915, he resigned from the cabinet altogether a few months later and took off to head an infantry battalion on the Western Front. “I am finished!” Churchill supposedly remarked. By 1917, however, he had received a new cabinet post. From there, though his political opponents delighted in shouting out “Remember the Dardanelles” in the House of Commons, he slowly worked his way back up, culminating in his appointment as prime minister in 1940 when Britain stood essentially alone in the fight against Nazi Germany.

7. Three separate national identities were forged at Gallipoli.

Despite having just gained a large (albeit incomplete) measure of independence from Britain, Australians and New Zealanders did not necessarily identify themselves as distinct until the horrors of Gallipoli awakened their national consciousness. Since 1916, the two countries have held an Anzac Day every April 25, named for the Australian and New Zealand Army Corps (ANZAC) that fought in the campaign. The holiday, somewhat akin to Memorial Day in the United States, commemorates those who have died in war and is celebrated, among other things, with a dawn service, veterans’ marches, the wearing of red poppies and the gambling game two-up. A heightened sense of nationalism also emerged among the victors at Gallipoli, which Atatürk and his cohorts used to great effect in founding the independent Republic of Turkey out of the ashes of the Ottoman Empire. Australians, New Zealanders and Turks all commonly make pilgrimages to the battlefield, now a protected national park with numerous gravesites and memorials.

Australian soldiers on the beach at Anzac Cove on April 25, 1915. (Credit: Philip Schuller/The AGE/Fairfax Media via Getty Images)

8. The last Gallipoli survivor made it to the 21st century.

Having lied about his age to enlist, 16-year-old Alec Campbell arrived at Gallipoli in October 1915, only to fall ill with a bad case of the mumps. Subsequently discharged as medically unfit, he spent the rest of his life in his native Australia, working on a cattle station and then as a carpenter before getting his economics degree and joining the civil service. Of the roughly 1 million British, French, Australian, New Zealand, Indian, Canadian, African, Ottoman and German men who took part in the Gallipoli campaign, an estimated 110,000 died on the battlefield. Of the rest, only a handful lived to see the 21st century. Campbell was the last known survivor, finally succumbing in May 2002 at the age of 103.