On 2 May 1915, August von Mackensen launched the Gorlice-Tarnow Offensive.
By the end of the month, his forces neared Przemyśl, which had been captured by the Russians from Austria-Hungary on 22 March 1915.
KMK Battery 6 took part in the bombardment of forts X, Xa, XI, and XIa, opened on 30 March.
Two days later, the Germans took and held forts X, Xa, and XI against counterattack, compelling the Russians to abandon Przemyśl.
German troops entered the city on 3 June, then took the remaining forts two days later.
From 8 August, KMK Battery 6 supported the XXXX Reserve Corps's attack on Kaunas Fortress by bombing Kaunas's three westernmost forts.
Although the German siege artillery's shelling of Kaunas was slow, the fortifications were outdated and were easily destroyed.
By 18 August, Kaunas was overrun by the Germans.
The next month, KMK Battery 6 was moved to the Serbian front to support a crossing of the Danube by the 11th Army.
Firing began on 6 October, and the Germans crossed the next day to take Belgrade.

To the south, KMK Batteries 3 and 5 participated in the siege of Novogeorgievsk, which the Germans had surrounded on 10 August.
On 13 August, KMK Batteries 3 and 5 attacked with the siege guns from the north, shelling forts XIV, XV, and XVI.
On 16 August, German infantry stormed forts XV and XVI as the artillery attacked them.
A single 42 cm shell struck German troops attacking Fort XV, resulting in heavy casualties, but the Germans took the forts.
The Russians abandoned the outer ring on 18 August, allowing the Germans to open a hole in the inner ring and capture Novogeorgievsk the next day.
In response, the Russians abandoned fortresses wholesale during the Great Retreat.
At Grodno, KMK Batteries 3, 5, and 6 were not even fully emplaced when the fortress was evacuated on 3 September.
On 2 May 1915, August von Mackensen launched the Gorlice-Tarnow Offensive. By the end of the month, his forces neared Przemyśl, which had been captured by the Russians from Austria-Hungary on 22 March 1915. KMK Battery 6 took part in the bombardment of forts X, Xa, XI, and XIa, opened on 30 March. Two days later, the Germans took and held forts X, Xa, and XI against counterattack, compelling the Russians to abandon Przemyśl. German troops entered the city on 3 June, then took the remaining forts two days later. From 8 August, KMK Battery 6 supported the XXXX Reserve Corps's attack on Kaunas Fortress by bombing Kaunas's three westernmost forts. Although the German siege artillery's shelling of Kaunas was slow, the fortifications were outdated and were easily destroyed. By 18 August, Kaunas was overrun by the Germans. The next month, KMK Battery 6 was moved to the Serbian front to support a crossing of the Danube by the 11th Army. Firing began on 6 October, and the Germans crossed the next day to take Belgrade.
To the south, KMK Batteries 3 and 5 participated in the siege of Novogeorgievsk, which the Germans had surrounded on 10 August. On 13 August, KMK Batteries 3 and 5 attacked with the siege guns from the north, shelling forts XIV, XV, and XVI. On 16 August, German infantry stormed forts XV and XVI as the artillery attacked them. A single 42 cm shell struck German troops attacking Fort XV, resulting in heavy casualties, but the Germans took the forts. The Russians abandoned the outer ring on 18 August, allowing the Germans to open a hole in the inner ring and capture Novogeorgievsk the next day. In response, the Russians abandoned fortresses wholesale during the Great Retreat. At Grodno, KMK Batteries 3, 5, and 6 were not even fully emplaced when the fortress was evacuated on 3 September.
Big Bertha (howitzer)