Mar 9 Bulgarian Tsar Ivan Asen II defeats Theodore of Epirus near the village of Klokotnitsa May 2 William de Braose, 10th Baron Abergavenny is hanged by Prince Llywelyn the Great Jul 27 Treaty of San Germano between Emperor Frederik II & Pope Gregory IX Aug 31 Bishop Willebrand of Utrecht grants Swells state justice 1229 Historical Events by Year 1231