1140s (1140–1149): political upheaval, crusading, and cultural change

Key events

• Capture of Edessa (1144) — The fall of the Crusader principality to forces under Imad al-Din Zengi spurred calls in Europe for a major military response.
• The Second Crusade (1147–1149) — Proclaimed by Pope Eugene III and preached by Bernard of Clairvaux, armies from France and Germany campaigned in the Levant and Iberia with mixed results.
• Siege and capture of Lisbon (1147) — Anglo-Norman and other crusading contingents assisted Afonso I of Portugal in taking Lisbon from Muslim control, an enduring gain for the Portuguese polity.
• Almohad rise (1147) — The new Almohad movement, led by Abd al-Mu'min after Ibn Tumart's doctrine, displaced the Almoravids and took Marrakesh, reshaping western Islamic politics.
• Byzantine succession (1143) — The death of John II Komnenos led to Manuel I Komnenos becoming emperor and pursuing an energetic foreign policy toward the West and the Balkans.
• The Anarchy in England — The civil war between King Stephen and Empress Matilda continued to produce sieges, changing allegiances and the temporary capture of Stephen at Lincoln (1141).
• Treaty of Shaoxing (1141) — In East Asia, the Southern Song dynasty concluded peace with the Jurchen-led Jin dynasty, marking a major settlement in China.

Politics and warfare

The decade saw simultaneous pressures on multiple frontiers. In the Levant the loss of Edessa prompted the Second Crusade; armies under Louis VII of France and Conrad III of Germany suffered from poor logistics and failed notably at the Siege of Damascus (1148), leaving the balance of power little changed. Iberian campaigns combined local reconquest with the participation of transnational crusaders, exemplified by Lisbon. North Africa experienced a decisive change as the Almohads supplanted the Almoravids, affecting Iberian-Muslim relations. In Western Europe and England feudal contestation and succession crises produced localized warfare and political fragmentation.

Religion, learning and culture

Religious leaders and monastic networks shaped public life. Bernard of Clairvaux emerged as the most influential spiritual voice of the decade, promoting the crusade and influencing ecclesiastical affairs. Monastic reform movements continued to affect ecclesiastical discipline and literacy. In architecture and liturgy the early Gothic style, associated with rebuilding projects such as Saint-Denis under Abbot Suger, began to alter church design and the experience of worship. Vernacular literature and the beginnings of courtly lyric poetry also gained ground in parts of France and Iberia, while scholastic methods developed in cathedral schools and early universities.

Legacy

The 1140s established patterns felt through the later twelfth century: expanded, though not always successful, crusading activity; the consolidation of new dynasties in North Africa and Iberia; and a renewed Byzantine engagement with western powers. Military successes and failures of this decade informed later diplomacy and conflict, while architectural and intellectual shifts contributed to long-term cultural transformations in Europe and beyond.