He proposed a roughly hexagonal fort with a hornwork , in the Dutch style of fortification .
The next proposal to build a fortification on the island was made by the Italian military engineer Antonio Maurizio Valperga in 1670 .
military engineer proposed a roughly hexagonal fort with a hornwork , in the Dutch style of fortification .
The next proposal to build a fortification on the island was made by the Italian military engineer Antonio Maurizio Valperga in 1670 .