Its initial overall aims were to tie down German defensive forces in the region, but without suggesting too great a threat to Southern France (until the Allies had decided whether or not to conduct landings there).

[9] Its aim was, during early 1944, to distract attention from a potential Allied invasion of Southern France (Operation Dragoon) by creating a fictional threat against Crete and Croatia.

[7] Zeppelin's "story" would be that the notional British Twelfth Army were preparing for an amphibious landing, from North Africa into The Balkans, supported by a Soviet overland invasion into Albania and Polish forces staged out of Italy.

Double agents relayed messages about troop movements, dummy formations and radio traffic were created and searches were conducted for local guides and maps, as would be made in preparation for a real invasion.

[4] Dummy formations were created in Italy and Libya, Colonel Victor Jones began depicting both an Armoured and Airborne divisions near Tobruk for the first stage of the operation.

The story passed to the Germans was that radio messages would inform friendly leaders in Yugoslavia of the intended invasion dates and any delays.

A naval exercise, involving sixty ships, was run between 9 and 11 June which included embarking thousands of men and vehicles from the US 91st Infantry Division.

From 24 June the Allies began to wind down Vendetta with the story that due to German forces remaining in the south of France (rather than moving to Normandy) that the invasion had been delayed.

[15] The final phase of Zeppelin was codenamed Turpitude, the story for which was an overland invasion of Greece by British troops via Turkey and the Soviet Union via Bulgaria.

[19][20] Instead, Zeppelin helped the Allies achieve their objective by convincing the Germans of the threat of small invasions, stopping them from removing the defensive forces.

Vendetta's various deceptions, coupled with political overtures in Spain (Operation Royal Flush), created what German intelligence called "wealth of alarming reports".

In mid-June the German command decided that although the Allies had enough troops in North Africa to effect an invasion they lacked the landing craft to actually undertake the operation.

[17] Despite this, the reports had held enough credibility in late May and early June that, on the eve of the Normandy Landings, German divisions were deploying in defensive positions along the southern coast.

The ambassador's report, which included details of Allied military buildup in the area, was treated with scepticism by German high command who were unable to verify some of the information.

However, the German intelligence apparatus issued warnings of probable Allied operations in the region, and requested "exceptional vigilance" from forces stationed there.