Soldiers of the Lithuanian Army's Grand Duchess Birutė Uhlan Battalion and National Defence Volunteer Forces staged a 1945 battle between Lithuanian partisans and Soviet NKVD forces that originally took place in Kalniškės forest near Lazdijai.

The battle is seen as a breaking point in Lithuania's partisan resistance to the Soviet occupation, although details about have been subject to ideological distortions. The NKVD claims in its official documents that its force lost 4 men and 7 were injured, although witnesses say the actual numbers were in the hundreds.

According to Lithuania's Genocide and Resistance Study Centre, the Kalniškės battle involved between 100 and 120 partisans, led by Jonas Neifalta-Lakūnas, and several times bigger force of NKVD 220th Border Regiment.

During the exercise, intended to recreate the circumstances of 70 years ago, the "NKVD" force killed all the "partisans", but not without sustaining heavy losses: over a third of its men. The losses were tracked using the so-called MILES system (Multiple Integrated Laser Engagement System).

The experiment battle was smaller than the real thing: some 20 National Defence Volunteer Force soldiers played the partisans; they were "attacked" by 85 soldiers of the Grand Duchess Birutė Uhlan Battalion, the so-called OPFOR (opposing force) whose role is to play enemy in military exercises.