Marie Petrušáková was born to a Volhynian Czech family on 3 December 1920 in Horodenka, Stanisławów Voivodeship, Poland (today in Ivano-Frankivsk Oblast, Ukraine).

[1] Ljalková's first combat experience came during the three-day Battle of Sokolovo (8–11 March 1943), during which she was pinned down under fire from Nazi machine guns for hours on the melting ice of the Mzha River [uk].

Unable to see in the darkness, she estimated the location of the enemy, aimed her Tokarev SVT-40 sniper rifle, and eliminated the machine gun nest.

[5][6] Her performance was even noticed by Nazi anti-Czechoslovak propaganda in the occupied Czech lands, which sought portray the Czechoslovak military unit as outlandish.

She eventually attained the rank of colonel, but due to health problems she left the army and started to work as a tour guide for Russian-speaking tourists.