In his plans he inclined to the Dutch rather than the Italian school of fortification.

He published in 1645.
At the close of the sixteenth century, the Dutch had been forced to resort to military defences to protect themselves against the aggressions of the Spaniards.

As the Dutch were inferior in other military means, fortification became one of the vital resources of the country.

Their works, however, thrown up in much haste, were in many respects defective, although well adapted to the exigencies of the time.
Freytag, their principal engineer, wrote in 1630.

Some of his improvements were introduced into France by Pagan.