Italy expelling Lodovico Sforza from Milan. With French success seemingly assured, the Pope determined to deal drastically with Romagna, which although nominally under papal rule was divided into a number of practically independent lordships on which Venice, Milan, and Florence cast hungry eyes. Cesare, empowered by the support of the French, began to attack the turbulent cities one by one in his capacity as nominated gonfaloniere (standard bearer) of the church. But the expulsion of the French from Milan and the return of Lodovico Sforza interrupted his conquests, and he returned to Rome early in 1500. The Jubilee (1500) In the Jubilee year 1500, Alexander ushered in the custom of opening a holy door on Christmas Eve and closing it on Christmas Day the following year. After consulting with his Master of Ceremonies, Johann Burchard, Pope Alexander VI opened the first holy door in St. Peter's Basilica on Christmas Eve 1499, and papal representatives opened the doors in the other three patriarchal basilicas. For this, Pope Alexander had a new opening created in the portico of St. Peter's and commissioned a marble door. Alexander was carried in the sedia gestatoria to St. Peter's. He and his assistants, bearing candles, processed to the holy door, as the choir chanted Psalm 118:19–20. The pope knocked on the door three times, workers moved it from the inside, and everyone then crossed the threshold to enter into a period of penance and reconciliation. Thus, Pope Alexander formalized the rite and began a longstanding tradition that is still in practice. Similar ceremonies were held at the other three basilicas. Alexander instituted a special rite for the closing of a holy door, as well. On the Feast of the Epiphany in 1501, two cardinals began to seal the holy door with two bricks, one silver and one gold. Sampietrini (basilica workers) completed the seal, placing specially-minted coins and medals inside the wall. Slavery While the explorers of Spain imposed a form of slavery called "encomienda" on the indigenous peoples they met in the New World, some popes had spoken out against the practice of slavery. In 1435, Pope Eugene IV had issued an attack on slavery in the Canary Islands in his papal bull Sicut dudum, which included the excommunication of all those who engaged in the slave trade with native chiefs there. A form of indentured servitude was allowed, being similar to a peasant's duty