Ravenna then gradually came under the direct authority of the Popes, although this was contested by the archbishops at various times. Pope Adrian I authorized Charlemagne to take away anything from Ravenna that he liked, and an unknown quantity of Roman columns, mosaics, statues, and other portable items were taken north to enrich his capital of Aachen. In 1198 Ravenna led a league of Romagna cities against the Emperor, and the Pope was able to subdue it. After the war of 1218 the Traversari family was able to impose its rule in the city, which lasted until 1240. After a short period under an Imperial vicar, Ravenna was returned to the Papal States in 1248 and again to the Traversari until, in 1275, the Da Polenta established their long-lasting seigniory. One of the most illustrious residents of Ravenna at this time was the exiled Florentine poet Dante. The last of the Da Polenta, Ostasio III, was ousted by the Republic of Venice in February 1441, and the city was annexed to the Venetian territories in the Treaty of Cremona. Ravenna was ruled by Venice until 1509, when the area was invaded in the course of the Italian Wars. In 1512, during the Holy League wars, Ravenna was sacked by the French following the Battle of Ravenna. Ravenna was also known during the Renaissance as the birthplace of the Monster of Ravenna. After the Venetian withdrawal, Ravenna was again ruled by legates of the Pope as part of the Papal States. The city was damaged in a tremendous flood in May 1636. Over the next 300 years, a network of canals diverted nearby rivers and drained nearby swamps, thus reducing the possibility of flooding and creating a large belt of agricultural land around the city. Modern age Apart from another short occupation by Venice (1527–1529), Ravenna was part of the Papal States until 1796, when it was annexed to the French puppet state of the Cisalpine Republic, (Italian Republic from 1802, and Kingdom of Italy from 1805). It was returned to the Papal States in 1814. Occupied by Piedmontese troops in 1859, Ravenna and the surrounding Romagna area became part of the new unified Kingdom of Italy in 1861. During World War II, the town suffered severe damage. Fifty-two Allied bombing raids during the course of the Second World War had taken their toll, destroying some of Ravenna’s noteworthy, unequalled early