The Ilinden-Preobrazhenie Uprising against the Ottoman Empire begins.

The Ilinden–Preobrazhenie Uprising, or simply the Ilinden Uprising of August - October 1903 (Bulgarian: Илинденско-Преображенско въстание, Ilindensko-Preobrazhensko vastanie; Macedonian: Илинденско востание, Ilindensko vostanie; Greek: Εξέγερση του Ίλιντεν, Eksegersi tou Ilinden), was an organized revolt against the Ottoman Empire, which was prepared and carried out by the Internal Macedonian-Adrianople Revolutionary Organization, with the support of the Supreme Macedonian-Adrianople Committee. The name of the uprising refers to Ilinden, a name for Elijah's day, and to Preobrazhenie which means Transfiguration. The revolt lasted from the beginning of August to the end of October and covered a vast territory from the eastern Black Sea coast to the shores of Lake Ohrid.The rebellion in the region of Macedonia affected most of the central and southwestern parts of the Monastir Vilayet receiving the support mainly of the local Bulgarian peasants, and to some extent of the Aromanian population of the region. Provisional government was established in the town of Kruševo, where the insurgents proclaimed the Kruševo Republic, which was overrun after just ten days, on August 12. On August 19, a closely related uprising organized by Bulgarian peasants in the Adrianople Vilayet led to the liberation of a large area in the Strandzha Mountains, and the creation of a provisional government in Vassiliko, the Strandzha Republic. This lasted about twenty days before being put down by the Turks. The insurrection engulfed also the vilayets of Kosovo and Salonika.By the time the rebellion had started, many of its most promising potential leaders, including Ivan Garvanov and Gotse Delchev, had already been arrested or killed by the Ottomans, and the effort was quashed within a couple of months. The rebellion was supported by armed detachments which had infiltrated its area from the territory of the Principality of Bulgaria. The survivors managed to maintain a guerrilla campaign against the Turks for the next few years, but its greater effect was that it persuaded the European powers to attempt to convince the Ottoman sultan that he must take a more conciliatory attitude toward his Christian subjects in Europe.

The uprising is celebrated today in both Bulgaria and North Macedonia as the peak of their nations’ struggle against the Ottoman rule and thus it is still a divisive issue. While in Bulgaria it is considered as a general rebellion prepared by the joint revolutionary organization of the Bulgarians in the Ottoman Empire, with a common goal autonomy for Macedonia and Adrianople regions, in North Macedonia it is assumed that there were in fact two separate uprisings. They were carried out by two different peoples with a diverse goals and practically the Macedonians were striving for their independence. Although the ideas of separate Macedonian nation were supported then only by a handful of intellectuals abroad, the post-WWII Macedonian rendition of history has reappraised allegedly the Ilinden uprising as an anti-Bulgarian revolt led by ethnic Macedonians. Calls for common celebrations did little to change this state of affairs.