'Gradient I' was a British special forces attack by elements of No. 9 Commando against the bridge connecting Lussin (Losinj) and Cres islands in the Adriatic Sea off the Dalmatian coast of German-occupied Yugoslavia (9/10 August 1944).

The object of the undertaking was the destruction of the swing bridge between the islands of Lussino Piccolo and Lussino Grande, and thus block the channel, which would require German vessels operating between the Istrian peninsula and coastal Yugoslavia to take a longer route and, in the case of ships travelling to the south, put them within the range of Allied naval forces at Ancona.

A 109-man force of Lieutenant Colonel R. J. F. Tod’s No. 9 Commando left Ancona in one motor gun boat and three motor torpedo boats and. One party was to seize and destroy the bridge while a second, using bicycles for transport, was to attack and destroy the local garrison. There was no opposition at the bridge, which was destroyed, and two Italian guards were taken prisoner. The local garrison could not be found so the bicycle party destroyed the local telephone exchange and returned with documents of possible interest and some civilians for questioning.

On its way back to Ancona, the British party rescued a US pilot who had spent a week adrift in the Adriatic.