In his earlier works we find many of the errors of his predecessors; but a gradual change seems to have been wrought in his mind by reflection and experience, and these faults were soon remedied and a new and distinct system developed.

Vauban has left no treatise upon his favorite art, and his ideas upon fortification have been deduced from his constructions, and from detached memoirs left among his papers.

The nature of his labors, and the extent of his activity and industry, may be imagined from the fact that he fought one hundred and forty battles, conducted fifty-eight sieges, and built or repaired three hundred fortifications.

His memoirs, found among his manuscript papers, on various military and political subjects, are numerous, and highly praised even at the present day.

But his beautiful and numerous constructions, both of a civil and military character, are real monuments to his genius.