In 1687, the Parthenon was extensively damaged in the greatest catastrophe to befall it in its long history. The Venetians sent an expedition led by Francesco Morosini to attack Athens and capture the Acropolis. The Ottoman Turks fortified the Acropolis and used the Parthenon as a gunpowder magazine – despite having been forewarned of the dangers of this use by the 1656 explosion that severely damaged the Propylaea – and as a shelter for members of the local Turkish community. On 26 September a Venetian mortar, fired from the Hill of Philopappus, blew the magazine up and the building was partly destroyed. The explosion blew out the building's central portion and caused the cella's walls to crumble into rubble. Greek architect and archaeologist Kornilia Chatziaslani writes that "...three of the sanctuary’s four walls nearly collapsed and three-fifths of the sculptures from the frieze fell. Nothing of the roof apparently remained in place. Six columns from the south side fell, eight from the north, as well as whatever remained from eastern porch, except for one column. The columns brought down with them the enormous marble architraves, triglyphs and metopes." About three hundred people were killed in the explosion, which showered marble fragments over nearby Turkish defenders and caused large fires that burned until the following day and consumed many homes. Accounts written at the time conflict over whether this destruction was deliberate or accidental; one such account, written by the German officer Sobievolski, states that a Turkish deserter revealed to Morosini the use to which the Turks had put the Parthenon expecting that the Venetians would not target a building of such historic importance. Morosini was said to have responded by directing his artillery to aim at the Parthenon. Subsequently Morosini sought to loot sculptures from the ruin and caused further damage in the process. Sculptures of Poseidon and Athena's horses fell to the ground and smashed as his soldiers tried to detach them from the building's west pediment. The following year, the Venetians abandoned Athens to avoid a confrontation with a large force the Turks had assembled at Chalcis; at that time, the Venetians had considered blowing up what remained of the Parthenon along with the rest of the Acropolis to deny its further use as a fortification to the Turks, but that idea was not pursued. After the Turks had recaptured the Acropolis they used some of the rubble produced by this explosion to erect a smaller mosque within the shell of the ruined Parthenon. For the next century and a half, portions of the remaining structure were looted for building material and any remaining objects of value. The 18th century was a period of Ottoman Turk stagnation; as a result, many more Europeans found access to Athens, and the picturesque ruins of the Parthenon were much drawn and painted, spurring a rise in philhellenism and helping to arouse sympathy in Britain and France for Greek independence. Amongst those early travellers and archaeologists were James Stuart and Nicholas Revett, who were commissioned by the Society of Dilettanti to survey the ruins of classical Athens. What they produced was the first measured drawings of the Parthenon published in 1787 in the second volume of Antiquities of Athens Measured and Delineated. In 1801, the British Ambassador at Constantinople, the Earl of Elgin, obtained a firman (edict) from the Sultan to make casts and drawings of the antiquities on the Acropolis, to demolish recent buildings if this was necessary to view the antiquities, and to remove sculptures from them. Although the existence of the firman is doubtful, as the original document has not been rescued, he took this as permission to collect all the sculptures he could find. He employed local people to detach them from the building itself; a few others he collected from the ground, and some smaller pieces he bought from local people. The detachment of the sculptures caused further irreparable damage to what was left of the building, as some of the frieze blocks were sawn in half to lessen their weight for shipment to England.