page_title: List of military disasters
section_title: Medieval era
hierarchical_section_title: List of military disasters / Medieval era
caption_attribution_description: Battle of Legnica (legnitz) 1241. From Legend of Saint Hedwig Legend: "hic pugnat dux henricus filius sanctae hedwigis cum thartaris in campo quod dicitur wolstat" (en: Here Duke Henry, the son of St. Hedwig, is in battle with the Tartans in the field which is called Wahlstatt; de: Hier kämpft Herzog Heinrich, Sohn der Hl. Hedwig, gegen die Tartaren im Feld, das Wahlstatt genannt wird.)
context_page_description: In this list a military disaster is the unexpected and sound defeat of one side in a battle or war, sometimes changing the course of history.
  Military disasters in this list can range from a strong army losing a major battle against a clearly inferior force, to an army being surprised and defeated by a clearly superior force, to a seemingly evenly matched conflict with an extremely one sided result. A military disaster could be due to bad planning, bad execution, bad weather, general lack of skill or ability, the failure of a new piece of military technology, a major blunder, a brilliant move on the part of the enemy, or simply the unexpected presence of an overwhelming enemy force.
  One definition of military disaster describes the presence of two or three factors:
  chronic mission failure
  successful enemy action,
  total degeneration of a force's command and control structure
  According to this definition, two particular characteristics are not necessary for an event to be classified as a military disaster:
  enormous loss of life
  having greater casualties than the enemy
context_section_description: The Battle of Salsu in 612, during the second Goguryeo-Sui War, between the Korean kingdom of Goguryeo and the Chinese Sui Dynasty. Goguryeo cavalry forces defeated the massive Sui army at the Salsu River (modern name: Chongchon River).
  The Battle of Yarmouk in 636, where the bulk of the Byzantine military along with their Christian Arab allies are destroyed by the Rashidun Army under Khalid ibn al-Walid, permanently costing the Eastern Roman Empire the Levant.
  The Battle of al-Qādisiyyah in 636, in which the Arab Muslim army decisively defeated the Sassanid army, resulting in the Islamic conquest of Persia and the nigh-collapse of the Sassanid Empire.
  The Battle of Tours in 732. The Muslim Moors marched into southern France meeting no foes, until encountering the Christian Frankish forces led by Charles Martel at Tours. Despite the Moorish advantage over the Franks militarily, they were defeated decisively by the Franks.
  The Battle of Pliska in 811. Byzantine forces were ambushed by a Bulgarian force, leading to the death of the Byzantine Emperor and greatly increased the Bulgarian power in the Balkans.
  The Battle of Achelous in 917. A Byzantine army of 30,000 men was tactically outwitted by a smaller Bulgarian force, causing the death of much of the Byzantine force in one of the bloodiest battles in the Middle Ages. The bones of tens of thousands who perished could be seen on the battlefield 75 years later.
  The Battle of Arcadiopolis in 970. A large force of 30,000 Kievan Rus allied with Bulgarians, Pechenegs and Magyars was defeated by a 12,000 strong Byzantine force through an ambushing tactic. This ended the Hungarian invasions of Europe.
  The Battle of Kleidon in 1014. A large Bulgarian force was destroyed by a Byzantine force in the Belasitsa Mountains. This encounter greatly reduced the ability of the Bulgarian state to resist and essentially led to the fall of the First Bulgarian Empire.
  The Battle of Stamford Bridge in 1066. A Norwegian army under king Harald Hardrada is destroyed by an Anglo-Saxon army under King Harold Godwinson. The battle is so costly for the Norwegians that only a fraction of the fleet used to transport the army is needed to pick up the survivors.
  The Battle of Hastings in 1066. The Anglo-Saxon King Harold is slain in battle against the Normans led by William the Conqueror, resulting in the Norman Conquest of England.
  The Battle of Manzikert in 1071. The Byzantine Empire suffers a humiliating defeat at the hands of the Seljuks, resulting in the capture of Emperor Romanos IV and Turkish settlement of Anatolia.
  The Battle of Didgori in 1121. David IV of Georgia, with 55,600 soldiers, routs the massive (100,000 minimum, more likely 250,000) army of the Great Seljuk Empire. As a result, the Kingdom of Georgia obtains large swaths of Seljuk territory, including Tbilisi.
  The Battle of Hattin in 1187, where overconfident Crusader forces from Jerusalem became trapped in a waterless desert area, and thus became easy prey for the Saracen forces of Salah-ud-din (Saladin)
  The Battle of Las Navas de Tolosa, known in Arab history as the Battle of Al-Uqab (Arabic: معركة العقاب‎), took place on 16 July 1212 and was an important turning point in the Reconquista and in the medieval history of Spain. The Christian forces of King Alfonso VIII of Castile were joined by the armies of his rivals, Sancho VII of Navarre and Peter II of Aragon in battle against the Almohad Muslim rulers of the southern half of the Iberian Peninsula. The al-Nasir (Miramamolín in the Spanish chronicles) led the Almohad army, made up of people from all over the Almohad Caliphate.
  The Battle of Kalka River, 1223. A Mongol army obliterates an allied Kievan-Rus'/Cuman army at a river crossing on the Kalka in the Ukraine. The Mongols draw the Russo-Cuman force out until they are overextended, then attack with their heavy cavalry and destroy the allied forces in detail. The Mongols capture several Russian princes and ritually execute them by crushing them beneath a feasting table on which the Mongol leaders dance and feast.
  The Battle of Le
caption: Mongol invasion of Poland (late 1240–1241) culminated in the Battle of Legnica
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