On November 5, 1916, the emperors of Germany and Austria-Hungary issued a proclamation that promised a kingdom of Poland on the Polish lands that had been part of the Russian empire, and the promise was made in order to raise soldiers and to organise the economy of the occupied territory behind the eastern front. The text was short. The offer was vague. It named no borders and no monarch and left the army and the foreign policy in the hands of the two empires.
Poland had been divided between Russia and Prussia and Austria at the end of the eighteenth century, and the largest part had been under Russian rule, and the war had put the whole of that part under German and Austrian occupation by the end of 1915. The occupiers wanted men and raw materials. A council of state was set up in Warsaw in January 1917 and a regency followed, but the two empires could not agree on a king, and the new bodies had little power, and the oath that the Polish forces were asked to swear caused a crisis in the summer of 1917 when many refused it.
The promise was overtaken by events. President Woodrow Wilson put an independent Poland with access to the sea among his conditions for peace in January 1917, and the Russian revolution and then the collapse of the eastern front changed the ground entirely, and in November 1918 the German and Austrian armies went home and Polish leaders took power in Warsaw. Independence came on the strength of that collapse, and not on the paper of 1916.
The proclamation was the first time in the war that a Polish state had been offered by an outside power, and it opened a competition among the powers to promise the Poles more, and it gave the Polish cause a place in the diplomacy of 1917 and 1918. It also made the point that such promises were made for the needs of the powers that made them. The lesson was clear. The borders of the new state were settled by fighting after 1918.