Marc Léopold Benjamin Bloch (; French: [maʁk blɔk]; 6 July 1886 – 16 June 1944) was a French historian. A founding member of the Annales School of French social history, he specialised in the field of medieval history and published widely on Medieval France over the course of his career. As an academic, he worked at the University of Strasbourg (1920 to 1936), the University of Paris (1936 to 1939), and the University of Montpellier (1941 to 1944).
Born in Lyon to an Alsatian Jewish family, Bloch was raised in Paris, where his father—the classical historian Gustave Bloch—worked at Sorbonne University. Bloch was educated at various Parisian lycees and the École Normale Supérieure, and from an early age was affected by the anti-semitism of the Dreyfus affair. During the First World War, he served in the French Army and fought at the First Battle of the Marne and the Somme. After the war, he was awarded his doctorate in 1918 and gained employment as a lecturer at the University of Strasbourg. There, he formed an intellectual partnership with modern historian Lucien Febvre. Together they founded the Annales School and began publishing the journal Annales d'histoire économique et sociale in 1929. Bloch was a modernist in his historiographical approach, and repeatedly emphasised the importance of a multidisciplinary engagement towards history, particularly blending his research with that on geography, sociology and economics, which was his subject when he was offered a post at the University of Paris in 1936.
During the Second World War Bloch volunteered for service, becoming responsible for the French Army's fuel supplies during the Phoney War. Involved in the Battle of Dunkirk and spending a brief time in Britain, he unsuccessfully attempted to secure passage to the United States. Back in France, where his ability to work was curtailed by new anti-Semitic regulations, he applied for and received one of the few permits available allowing Jews to continue working in the French university system. He had to leave Paris, and complained that the Nazis looted his apartment and stole his books; he was also forced to relinquish his position on the editorial board of Annales. Bloch worked in Montpellier until November 1942 when Germany invaded Vichy France. He then joined the French Resistance, acting predominantly as a courier and translator. In 1944, he was captured in Lyon and executed by firing squad. Several works—including influential studies like The Historian's Craft and Strange Defeat—were published posthumously.
Both as a result of his historical studies and his death as a member of the Resistance, Bloch was highly regarded by generations of post-war French historians and came to be called "the greatest historian of all-time". By the end of the 20th century, historians were making a more sober assessment of Bloch's abilities, influence, and legacy, arguing that there were flaws to his approach.