Peschiera was part of the so-called 'Quadrilatero' of strong core Austrian defences,[2] leaving the exposed eastern shore of Lake Garda an area of potential weakness, vulnerable to Italian infiltration.

[3] This might have involved a strike from the north end of the Lake up the valley of the Chiese river to threaten Trento and cut off the supply lines of the Austrian forces in the Veneto.

He first placed his flag on board the Hess, with its larger and more comfortable accommodation, but shifted his command to the more effective Speiteufel on 10 June as war appeared imminent.

On June 30, the Austrian ships bombarded the railway station at Desenzano, a supply and communications point for the Italian Volunteer Corps of Giuseppe Garibaldi, but caused only minor damage.

[3] More substantial action took place on July 2, at 5 am, when four Austrian gunboats, including the Hess and Franz Joseph, bombarded the centre of Gargnano,[6] where there was a strong concentration of Garibaldi's forces.

On 6 July, Italian volunteer forces, equipped with nine long-range guns borrowed from a coastal battery at Maderno, ambushed the Austrian gunboat Wildfang at Gargnagno.

[6] The next significant combat occurred on July 19 when the Italian paddle steamer Benaco head out from Salò for Gargnano towing the sailboat Poeta, both ships carrying reinforcement troops and loaded with supplies for the volunteers in the mountains of Valvestino and Tremosine.

The Benaco was suddenly attacked by two Austrian gunboats, the Wildfang and Schwarzschütze, which forced it in to shore near Gargnano, where most of the crew, troops and supplies were landed during the night.

[8] A second convoy from Salò, consisting in another sailboat escorted by the Italian flotilla, was forced back two days later by the Austrian gunboats Speiteufel, Uskoke and Wespe.

After skirmishes on the lake on 24 July, Manfroni learned that the Austrian army had abandoned Riva del Garda, which was one of his key supply points.