Year 1378 (MCCCLXXVIII) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. Events January–December January – Charles IV, Holy Roman Emperor, visits his nephew Charles V of France in Paris, to celebrate publicly the friendship between their two nations. January 13 – Balša II succeeds his brother, Durađ I, as ruler of Lower Zeta (modern-day Montenegro). March – In England, John Wycliffe tries to promote his ideas for Catholic reform by laying his theses before Parliament, and making them public in a tract. He is subsequently summoned before the Archbishop of Canterbury, Simon of Sudbury, at the episcopal palace at Lambeth, to defend his actions. April 9 – Following the death of Pope Gregory XI, and riots in Rome calling for a Roman pope, the cardinals, who are mostly French, elect Pope Urban VI (Bartolomeo Prignano, Archbishop of Bari) as the 202nd Pope. April 16 – Da'ud Shah succeeds his assassinated nephew, Aladdin Mujahid Shah, as ruler of the Bahmani Sultanate in modern-day southern India. Da'ud Shah is assassinated in the following month, and is succeeded by Mohammad Shah II. May – Uskhal Khan Tögüs Temür succeeds his father, Biligtü Khan Ayushiridara, as ruler of the Northern Yuan dynasty in Mongolia. July 21 – Ciompi Revolt: Discontented wool carders briefly take over the government of Florence. August 4 – Gian Galeazzo Visconti succeeds his father, Galeazzo II Visconti, as ruler of Milan. August 11 – Battle of the Vozha River: Prince Dmitri Ivanovich of Moscow resists a small invasion by the Mongol Blue Horde under Mamai. September – A contract is set up between Richard le Scrope, 1st Baron Scrope of Bolton and the mason Johan Lewyn, for the construction of Bolton Castle in the north of England. September 20 – Unhappy with Pope Urban's critical attitude towards them, the majority of the cardinals meet at Fondi, elect Clement VII as antipope, and establish a rival papal court at Avignon. This split within the Catholic Church becomes known as the Western Schism. France, Aragon, Castile and León, Cyprus, Burgundy, Savoy, Naples and Scotland choose to recognise Antipope Clement VII. Denmark, England, Flanders, the Holy Roman Empire, Hungary, northern Italy, Ireland, Norway, Poland and Sweden continue to recognise Pope Urban VI. November 10 – Estimated appearance date of Halley's Comet. November 29 – Charles IV, Holy Roman Emperor, dies in Prague. He is