Gorlice–Tarnów offensive

A Central Powers offensive in May–June 1915 that broke through Russian lines in Galicia and forced a major Russian retreat during World War I.

Artillery preparation: A bombardment intended to damage defenses, disrupt communications, and suppress opposing forces before an assault. A concentrated bombardment opened the offensive's breakthrough at Gorlice.
Erich von Falkenhayn: A German general who served as chief of the General Staff from 1914 to 1916. He supported the effort to stabilize the Eastern Front through a major strike against Russia.
Great Retreat (Russian): The Russian Army's withdrawal from Galicia, Poland, and Lithuania in 1915 under pressure from the Central Powers. The offensive initiated the chain of retreats that gave this Russian withdrawal its name.
Battle of Gorlice: The May 1915 battle in Galicia in which Central Powers forces broke through Russian defenses near Gorlice. The battle gave the offensive its name and marked its decisive initial breach.
Breakthrough (military): A military penetration that ruptures an enemy defensive line and creates opportunities to advance into its rear. The offensive became decisive when the Russian line was penetrated and could not be restored.
August von Mackensen: A German field marshal who commanded major Central Powers formations on the Eastern Front. He led the German Eleventh Army during the breakthrough operation.
Russian Poland: The westernmost region of the Russian Empire, a major battlefield during World War I. The Central Powers advanced into Russian Poland after taking Galicia.
Battle of Tarnów: A May 1915 engagement near Tarnów in Galicia during the Central Powers advance against Russian forces. Tarnów anchored the northern part of the breakthrough sector.
Infiltration tactics: A method of attack in which small units exploit gaps and weak points to penetrate defensive positions. German assault units used infiltration to exploit openings made by the bombardment.
Franz Conrad von Hötzendorf: The chief of the Austro-Hungarian General Staff during much of World War I. He sought German assistance after Austro-Hungarian forces suffered setbacks against Russia.

Linked from 4 pages