the latter on receipt of this news again entered rome on 21 march 1084, and succeeded in gaining possession of the greater part of the city and besieged the pope in the castle of sant' angelo, while, on 24 march, guibert was enthroned as pope in the church of st. john lateran as clement iii, and on 31 march guibert crowned henry iv as emperor at st. peter's. however, when the news was brought that gregory's norman ally, robert guiscard, duke of apulia and calabria, was hastening to his aid, henry fled rome with guibert and, in revenge for matilda of tuscany's staunch support for gregory and the reform party, ravaged her possessions in tuscany. pope gregory was liberated, but the people were incensed by the excesses of his norman allies, and he was compelled to leave rome. disappointed and sorrowing he withdrew to monte cassino, and later to the castle of salerno by the sea, in 1084, where he died in the following year, 25 may 1085.