'Gelignite' was a British unrealised plan for Lieutenant General Sir Richard McCreery’s 8^th Army to undertake operations in the northern part of Yugoslavia (February 1945).

There had been great disappointment in the Allied camp after the failure of the 'Olive' offensive of October 1944 by General the Hon. Sir Harold Alexander’s Allied Armies in Italy command to capture Bologna, but Alexander was already considering how his forces could break out of the limits imposed on them by the combination of northern Italy’s geography and the defence put up by the two armies of Generalfeldmarschall Albert Kesselring’s Heeresgruppe 'C' . Alexander’s preferred option, for implementation in February 1945, was 'Gelignite', which envisaged an amphibious offensive across the northern part of the Adriatic Sea to establish a link with the Yugoslav partisan forces of Marshal Josip Broz Tito in the western part of German-occupied Yugoslavia.

Alexander put his plans for immediate operations in Italy and also 'Gelignite' to a conference of senior Allied officers on 29 October 1944.

'Gelignite' was to be based on a two-part offensive on the left by Lieutenant General Mark W. Clark’s US 5^th Army on the Italian mainland, and on the right by the 8^th Army across the Adriatic. This would create a large pincer aimed at the destruction of the German forces in Italy by a converging movement on Trieste and Gorizia, the seizure of the port cities of Trieste and Fiume, and then a fast-moving advance over the Brenner pass into Austria and thus the capture of Vienna. Slightly greater detail about Alexander’s plan suggested that the 5^th Army would become responsible for the entire front within Italy with all the US and Brazilian troops, plus Generał dywizji Władysław Anders’s Polish II Corps, the Indian 8^th and 10^th Divisions and five Italian combat groups. The Indian divisions would be drawn into Allied Armies in Italy reserve for use on either front once the 1945 offensive had started. This would leave the 8^th Army with three corps (with nine divisions) for the thrust across the Adriatic.

Alexander next outlined a likely schedule: in the first phase, to be completed by the end of November, the 8^th Army would remove the German salient between Forlì and Monte Grande, during which Ravenna might be captured, and the 5^th Army would rest and prepare for its renewed offensive against Bologna; in the second phase, to be undertaken between 30 November and 15 December, the final effort would be made to take Bologna and Ravenna, but only if the phase was likely to achieve major success; and in the third phase the Allied force would be regrouped and trained for 'Gelignite'.

Alexander then delivered a report to General Sir Henry Maitland Wilson, the Allied supreme commander in the Mediterranean theatre, with additional points including Alexander’s belief that pressure from the Soviet forces to the north-east would force the Germans to pull back from the Dalmatian coast, and that he planned to pave the way for 'Gelignite' by sending in light forces to collaborate with the partisan forces in opening communications, desired to send a reconnaissance party of two staff officers and his naval liaison officer to examine the port of Split and its hinterland as soon as it was safe to do so, with similar reconnaissance undertakings to follow to Sibenik and Zadar, and finally to despatch engineer parties to carry out detailed surveys of the work that would need to be done.

Alexander assumed that Tito would agree to the concept, but he requested authorisation to communicate directly with Brigadier F. H. R. Maclean’s 37^th Military Mission at Tito’s headquarters.

After considerable argument for an against 'Gelignite', however, the Allied high command decided that the forces in Italy, which from 16 December were Clark’s Allied 15^th Army Group, should be concentrated on the defeat of Heeresgruppe 'C' and the capture of northern Italy. Wilson now believed that after the capture of Bologna, the German forces in north-western Yugoslavia should be pinned by air power to prevent their withdrawal to the north, and that the Allies should strengthen the partisan forces with supporting arms.

To give himself some operational flexibility Wilson wished to retain assault shipping for one reinforced division, or at least sufficient to permit Brigadier G. M. O. Davy’s Land Forces Adriatic command to continue minor harassing operations and to allow a possible amphibious 'right hook' on a brigade scale in support of the Allied Armies in Italy (from 12 December the 15^th Army Group) on the Adriatic coast. The British chiefs-of-staff accepted Wilson’s case, but not his request to retain assault vessels sufficient for the delivery of one division: Wilson was instead to retain 24 tank landing ships, and release 28 tank landing ships and 40 infantry landing craft and tank landing craft for operations elsewhere.

These directions were formalised in a directive of 2 December, and thus 'Gelignite' proceeded no further.