Suboficial
Szendzielarz was born in Stryj (Austrian Partition, now Lviv Oblast, Ukraine), then part of the Austro-Hungarian Empire and from 1919 to 1939 in Poland, into the family of a railway worker. After graduating from primary school in Lwów, he attended a biological-mathematical "gymnasium" in Lwów and then Stryj. After graduating, he volunteered for the Polish Army and completed Infantry Non-commissioned officer School in Ostrów Mazowiecka (1932), then Cavalry NCO School in Grudziądz. He was promoted to lieutenant and transferred to Wilno, where he assumed command of a squadron in the 4th Uhlan Regiment.