Corso Donati was a leader of the Black Guelph faction in 13th- and early 14th- century Florence. Bologna and Pistoia In the late thirteenth century, power in Florence and the other Tuscan cities was divided between the Podestà, an outsider who served as chief magistrate, and the guildmasters. Corso served as Podestà of Bologna in 1283 and 1288, and of Pistoia in 1289. In 1289, as captain of the people in Pistoia, he led a group of soldiers in a cavalry charge at the Battle of Campaldino, in which the Guelphs defeated the Ghibellines and cemented their control over Florence. Leader of the Black Guelphs In 1293, the merchants of Florence, led by Giano della Bella, prevented the nobility from taking the office of guildmaster. Corso led the noble faction which aligned with the working class against the merchants. In 1294 Corso was acquitted of killing a man in a fight; an angry mob came to della Bella seeking justice after the acquittal, but he sent them away whereupon they rioted and della Bella was exiled as having caused the riot. At that time, the Cerchi family, leaders of the merchant faction who had long feuded with the Donati, became allied with the White Guelphs while the Donati allied with the Black Guelphs, similar factions which had arisen in Pistoia. The leaders of both Guelph factions, including Corso, were exiled by the merchants in 1300, but the White Guelphs were soon allowed to return. Corso and the Black Guelphs petitioned Pope Boniface VIII for aid, and returned to Florence with Charles of Valois in November 1301, killing or exiling many White Guelphs. One of the exiled was the famous poet Dante Alighieri, who by marrying Gemma Donati had become a distant relative of Corso. Plots against the Black Guelphs Beginning in February 1303, Corso broke with the other Black Guelphs and joined the Cavalcanti, a family of White Guelphs, in calling for the examination of the finances of his former allies. This led to a new eruption of fighting in which forces from Lucca temporarily controlled Florence. Donati was one of twelve prominent Florentine citizens summoned by Pope Benedict XI in 1304 in an attempt to bring peace to the city; the White Guelphs and some Ghibellines were restored, although the Ghibellines were expelled again in 1306. In 1308 Corso was accused of plotting to overthrow the Florentine commune and