The Gorlice-Tarnow Offensive

The battle of Gorlice-Tarnow, 2-10 May 1915, was a rare breakthrough battle during the First World War. The German victory at Gorlice-Tarnow threatened the entire Russian line and eventually forced the abandonment of Russian Poland
The battle of Lemberg, 20-22 June 1915, was a short-lived Russian attempt to defend Lemberg in the period after the German breakthrough at Gorlice-Tarnow
The third battle of Warsaw, 5 August 1915, saw the Germans occupy Warsaw in the aftermath of their victory at Gorlice-Tarnow.
The siege of Novo-Georgievsk, 10-20 August 1915, saw a Russian garrison 90,000 strong captured by the Germans after the fall of Warsaw.