Kazimierz Siemienowicz

Kazimieras Simonavičius (Latin: Casimirus Siemienowicz, Polish: Kazimierz Siemienowicz, Belarusian: Казімір Семяновіч, born c. 1600 - c. 1651), was a Polish-Lithuanian general of artillery, gunsmith, military engineer, artillery specialist and pioneer of rocketry. Born in the Grand Duchy of Lithuania, he served the armies of the Polish-Lithuanian Commonwealth, a federation of Poland and the Grand Duchy, and in the armies of Frederick Henry, Prince of Orange, a ruler of the Netherlands. No portrait or detailed biography of him has survived and much of his life is a subject of dispute.

After contributing his expertise to several battles, Siemienowicz published Artis Magnae Artilleriae in 1650. This treatise, which discussed rocketry and pyrotechnics, remained a standard work in those fields for two centuries.