The new Uskok stronghold, screened by mountains and forests, was unassailable by cavalry or artillery. However, the fortress was admirably suitable to the lightly armed uskoks who were excellent in guerrilla warfare. The Martolos were employed by the Ottomans to discourage Uskok penetration of Turkish territory, which was not very profitable anyhow. Since the uskoks were checked on land and were rarely paid their annual subsidy, they resorted to acts of piracy. Large galleys could not anchor in the bay of Senj, which is shallow and exposed to sudden gales. So, the uskoks fitted out a fleet of swift boats, which were light enough to navigate the smallest creeks and inlets of the shores of Illyria. Moreover, these boats were helpful in providing the uskoks a temporary landing on shore. With these they were able to attack numerous commercial areas on the Adriatic. The uskoks saw their ranks swell as outlaws from all nations joined them. Eventually, the whole city of Senj lived from piracy. The expeditions were blessed in the local church and the monasteries of the Dominicans and the Franciscans received tithes from the loot.