1274

May 7 - The Second Council of Lyons, held by the leadership of the Roman Catholic Church convenes to consider the conquest of the Holy Land via Crusades and address the East-West Schism with the Byzantine church. The Council eventually approves a tithe to support efforts to conquer the Holy Land from Muslims, and reaches apparent resolution of the schism which ultimately proves unsuccessful.

November - The diet at Nuremberg orders that all crown estates seized since the death of Frederick II, Holy Roman Emperor be restored to Rudolph I of Germany; almost all European rulers agree, with the notable exception of King Otakar II of Bohemia, who had benefited greatly by conquering or otherwise coming into possession of
many of those lands.

Pope Gregory X decrees that conclaves (meetings during which the electors have no contact with the outside) should be used for papal elections, reforming the electoral process which had taken over three years to elect him.