European governments had long viewed Ottoman Empire as weak. But the French and British, the Ottomans’ opponents in World War I, decided the empire couldn’t outlast the war, and in 1915 moved toward splitting up the Levantine territories under Ottoman control. Sykes and Georges-Picot were charged with figuring out how. The agreement they came to—with the assent of their ally Russia—granted Russian control over present-day eastern Turkey. The French would influence or control southern Turkey, Lebanon, present-day Syria, and Northern Iraq. The British would dominate a corridor running from Egypt west through the Negev Desert, present-day Jordan, and most of what is now Iraq and Kuwait. Present-day northern Israel and the West Bank would become an international zone, though Britain would control the port of Haifa.

The map above tells most of the story. (Here’s a full version.) The agreement itself is rather drab to read, cloaked in diplomatic niceties—although the heavy focus on railroad-building rights harkens back to a time when rails, rather than oil, were the most important geopolitical infrastructure in the Fertile Crescent. Today, those train lines have atrophied.

The agreement was concluded in secret partly because it represented a betrayal of promises the British government had already made to Hussein bin Ali, the sharif of Mecca. During the war, in an effort to foment an Arab rebellion against the Ottomans, the British sought Hussein’s support by agreeing to back the creation of an independent Arab state, with a few caveats. In what is known as the McMahon-Hussein Correspondence, Britain laid out the conditions: It wanted to maintain rights in Baghdad and Basra, and it wanted to set aside pieces of present-day Syria, which it said were not fully Arab. The Arabs duly revolted against the Ottomans, with the help of the British military officer T.E. Lawrence. But after the war, the British would maintain that the correspondence did not represent a formal treaty, though Hussein and his family insisted it did. In any case, the promises made to Hussein were in irreconcilable conflict with the Sykes-Picot Agreement.

A further British promise incompatible with Sykes-Picot came later, on November 2, 1917, when U.K. Foreign Secretary Arthur James Balfour wrote to British Jewish leader Walter Rothschild, stating that the British government viewed “with favour the establishment in Palestine of a national home for the Jewish people, and will use their best endeavours to facilitate the achievement of this object.” That seemed in conflict with the international zone Sykes-Picot envisioned in the Levant.

In the meantime, Tsar Nicholas II had been overthrown in Russia. First, a provisional government ruled, but in November 1917—the same month the Balfour Declaration was sent—it was overthrown, and the Bolsheviks took power. They came across the text of the Sykes-Picot Agreement, and on November 23, 556 days after the deal was signed, published it in Pravda and Izvestia. Three days after that, The Manchester Guardian also published the text. The publication of the secret agreement was an embarrassment to the Allies, showing them carving up the Middle East, and in particular showing Britain making incompatible promises to Hussein and the Arabs as well as to the Zionists.