Supported the Jesuits and the decrees of the Council of Trent.
Appointed a committe of cardinals, including Saint Charles Borromeo, to clean up clerical abuses and reform the clergy.
Fought nepotism.
Worked to stir the European princes against the Turks, but could not get them to stop squabbling among themselves.
Sought to stop Protestantism by increasing the number and education of priests, and insuring that they were holy, disciplined and dedicated men.
Founded several Jesuit colleges and seminaries, training priests and missionaries.
Some historians have criticized Gregory for ordering the massacre of Huguenots on Saint Bartholomew's Day, 1572, but he knew nothing about it until it was done, and even his enemies agreed that he cried over the cruel act.
Founded the Congregatio Germanica in 1573 to safeguard the Catholic faith in Germany.
Approved the Congregation of the Oratory in 1574.
Revised the Julian calendar into the current Gregorian in 1578.
Approved the Barnabites in 1579.
Approved the Discalced Carmelites in 1580.
Revised and updated the Roman Martyrology in 1580.
He involved himself actively in the politics of Ireland, England, and France.
To raise funds for his political and building projects he confiscated many of the houses and property in the Papal States, which alienated him with the nobility and land owners, and caused general unrest.
The oldest surviving papal tiara dates from his pontificate.
![[Pope Gregory XIII]](pope0226.jpg "43kb jpg detail from the tomb of Pope Gregory XIII, by Camillo Rusconi, c.1723, Saint Peter's Basilica, Vatican; if you have information about this image, pleae email me; please do not write to ask about the image")