The 'Adzhimushkay Defensive Operation' was the Soviet defence and final loss of the Adzhimushkay quarry named after the Adzhimushkay suburb of Kerch during the Germany occupation of Crimea (16 May/30 October 1942).

In 1942 Adzhimushkay was a small mining suburb 3.1 miles (5 km) from the city of Kerch at the western end of Crimea, and was a complex of mines from which limestone had been extracted from 1830 by means of surface quarrying and underground shafts. Over the years the latter had created a network of tunnels known as the Great and Small Adzhimushkay Tunnels, and these were first used for military purposes by pro-Bolshevik armed groups during the Russian Civil War.

When the Germans occupied Kerch in November 1941, a group of Soviet partisans was already in occupation of the tunnels. On 8 May the Germans began their 'Orkan' (ii) operations to drive the Soviet forces from the Kerch peninsula and to take the city of Sevastopol. In the Kerch peninsula, the Soviet forces were overrun and suffered severe loss before the last of them were evacuated from the Kerch beach-head to the Taman peninsula. By 19 May, the fighting of regular forces in the area had come to an end, and in order to ensure the safest possible evacuation of Soviet troops across the Strait of Kerch, a defence group was left in Adzhimushkay under the command of Polkovnik Pavel M. Yagunov.

The group absorbed remnants of the retreating Soviet units, together with numerous civilians fleeing the city, and eventually grew to a strength of several thousand. When it became obvious that the beach-head at Kerch could not be held, the Adzhimushkay group found refuge in the quarry’s tunnel. It is estimated that more than 10,000 fled to the Great Adzhimushkay tunnel system, and 3,000 to the Small Adzhimushkay tunnel system. The larger portion of this force was led by Yagunov with two subordinate commanders, and the smaller part by three subordinate officers.

The tunnels were ill-suited for defence as no supplies had been pre-positioned in them, and all of the wells were located outside. Thus water supplies had to be seized by force as an armed sortie was needed to reach a well, and the Germans resisted these. The Soviet group attempted several counterattacks, including one that resulted in the defeat of the German occupation force in Adzhimushkay on the night of 8/9 July, but Yagunov was killed in that assault.

Most of the Soviet partisans were killed or died of 'natural causes' as the group ran out of ammunition, food and water, and therefore resorted to extreme survival techniques such as the preparation of flesh of livestock earlier killed in the mine entrances, and the gathering of water which condensed on the tunnels' ceilings. The defenders also attempted to dig their own wells within the tunnels, to a depth of some 46 ft (14 m) as they tried to reach the deeper water layer.

The Germans surrounded the quarry area with barbed wire entanglements, blocked the entrances and exits, and bombed and shelled them. General Hermann Ochsner, the chief of the German chemical forces, proposed the use of a non-lethal irritant gas to smoke out the partisans, but was denied permission to carry out the attack: some survivor testimonies later claimed otherwise.

On 30 October, German forces entered the tunnels and seized their remaining defenders. The estimates of the number of partisans who survived the 170-day siege and final clash vary between 48 to 300 of the initial total of some 13,000 Soviets.