Adam Freytag

He graduated gymnasium in Toruń.^[1] After receiving a scholarship from the city council, he studied at the University of Frankfurt, and then moved to the Leipzig University, where he obtained a master's degree.^[1]

He joined the military of the Dutch Republic during the Eighty Years' War under the command of Frederick Henry, Prince of Orange.^[1] He took part in the Siege of 's-Hertogenbosch in 1629. From 1629 to 1632, he studied at the medical faculty of the Leiden University, obtaining a doctorate in medicine.^[1]

During his stay in Leiden, he wrote Architectura militaris nova et aucta, the first manual of bastion fortifications of the so-called Old Dutch system, published in 1631. In 1632, he met future Grand Hetman of Lithuania Janusz Radziwiłł in Leiden.^[2]

Freytag soon joined Radziwiłł's regiment and took part in the Smolensk War between Poland and Russia in 1633–1634.^[2] After the war, in 1634, he returned to Toruń and became a teacher of mathematics and astronomy at the local gymnasium.^[2] Upon request from the city authorities, he assisted in the modernization of Toruń's fortifications.^[2] Soon, however, he returned to the Radziwiłł court, and began work on modernizing the fortifications of Biržai.^[2] After 1640, he was the military engineer and court physician of Janusz Radziwiłł.^[2] Later on, he taught mathematics in the gymnasium of Kėdainiai.^[2]