Year 1147 (MCXLVII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar.
April – Abd al-Mu'min destroys the Almoravid Empire after capturing Marrakech and killing the last emir, Ishaq ibn Ali.
The Siculo-Normans take control of Gabes.
October 25 – Battle of Dorylaeum, the Seljuq Turks defeat German crusaders under Conrad III.
The Second Crusade begins.
Eastern Europe
June – The Wendish Crusade fails to convert most of the Polabian Slavs.
The cities of Moscow and Vologda are first mentioned in written records.
Southern Europe
July 1–October 25 – with the support of English and Flemish Crusaders, Afonso I of Portugal besieges and conquers Lisbon (Siege of Lisbon). The same year, the troops of the young Portuguese kingdom take Sintra and Santarém (Conquest of Santarém) and sack Palmela.
September – Arrival of the German contingent of the Second Crusade before Constantinople; after a battle before the city walls, the Germans accept to be ferried over the Bosporus to Asia.
Roger II of Sicily takes Corfu from the Byzantine Empire, and pillages Corinth, Athens and Thebes.
October 7 – Almería, one of the most important maritime and commercial centers of al-Andalus, falls into Christian hands after two months of siege.
The Almohad general Berraz ibn Mohammad al-Masufi conquers Seville.
Consecration of the church of San Frediano in Lucca
Dore Abbey is founded.
Hildegard of Bingen founds the convent of Rupertsberg near Bingen.
Foundation of Jedburgh Abbey by David I of Scotland
May 9 – Minamoto no Yoritomo, Japanese shogun (d. 1199)
Emperor Guangzong of Song (d. 1200)
Hugh de Kevelioc, 3rd Earl of Chester (d. 1181)
Ibn Qudamah, Islamic scholar (d. 1223)
Shōkū, Buddhist leader (d. 1247)
King Stephen III of Hungary (d. 1172)
Taira no Munemori, Japanese warrior (d. 1185)
Wada Yoshimori, Japanese military commander (d. 1213)
probable – Raimbaut of Orange, troubadour (d. 1173)
January 13 – Robert de Craon, second Grand Master of the Knights Templar
April 6 – Frederick II, Duke of Swabia, (b. 1090)
April – Fannu, Almoravid Princess and warrior
September 19 – Igor II of Kiev
October 31 – Robert, 1st Earl of Gloucester, English politician (b. c. 1090)
December 25 – Guy II, Count of Ponthieu (b. c. 1120)
date unknown
John Capellanus, Scottish bishop
Comita II of Arborea, ruler of Arborea
Pietro Polani, 36th Doge of Venice
William fitz Duncan, Scottish prince
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