The article deals with the question of involving soldiers of garrison regiments to build fortifications in St. Petersburg and Kronstadt in the first third of the 18th century. Soldiers were recruited on the island of Kotlin in the 1710s, when large-scale construction works were launched there. The service- men did not perform hard tasks. Their number, compared with the total number of working people at that time was small. At that time recruitment of soldiers, most likely, was associated with secrecy as they were involved wherever ordinary workers did not want to be admitted.