 Pari gbolohun yii: Bi Siemienowicz ṣe kọ ọ, o nifẹ si ohun ija lati igba ewe, o si kẹkọọ ọpọlọpọ awọn imọ-jinlẹ lati mu imọ rẹ pọ si matematika, ẹrọ, hydraulics, faaji, optics, tactics. Ni ọdun 1632-1634 o kopa ninu Ogun Smolensk, ni Siege of Belaya labẹ Mikołaj Abramowicz ẹni ti o di ọdun 1640 akọkọ Lithuanian General of Artillery. Ó ṣeé ṣe kó jẹ pé ní ọdún 1644 ó kópa nínú : Ogun Ochmatów. 