Cattaro was next on the target for the British; a body of Montenegrin troops under Petar I Petrović-Njegoš a popular spiritual and military leader of the Serbian Orthodox church[5] from the Petrović dynasty had surrounded the place.

Saracen arrived first just outside Cattaro Bay but it was impossible to sail direct to the main fortress so Harper called on the local inhabitants to tow her along the rocky shore for 3 miles.

The British and Sicilians forced the passage between Herceg Novi and Fort Rosa and secured an anchorage some three miles inside the outer bay.

[6]: 141 On the evening of the 14th Harper left with two gunboats, the launch and barge of Bacchante and the boats of Saracen entered the inner bay where he was fired on from the Island of St George.

Then within fifteen minutes the Royal marines and the Sicilians under Captain Harper in several smaller craft attacked a French gunboat force off the island seizing all four.

[2][6]: 137 By now only the main fortress of Cattaro was left and Hoste, Harper and his assortment of allies – British, Croats, Montenegrins and Sicilians – surrounded the area.

However, he knew that politics would eventually play a role if and when the area was under allied control and therefore also had to try to satisfy the British commissioner in the region Lord Aberdeen by ensuring that the Austrians were the ones to end up with the spoils.

Hoste and Harper led their men in the difficult task of scattering batteries down the forbidding slopes of the Cattaro hills using block and tackle.

In an "unmilitary manner" after 3 weeks of great exertion by Bacchante and Saracens seamen in continuous rain an 18-pounder was hoisted to the summit on 23 December, a height of nearly 3,000 feet.

After ten days of shelling and no hope of relief the French surrendered to Hoste under honourable conditions and the British and Montenegrins took control of the fort and the town.