Italy entered the Second World War on 10 June 1940 and the plan was put into effect but at first, the local French authorities prevented the RAF Vickers Wellington bombers from taking off.

Wireless decrypts by the Government Code and Cypher School at Bletchley Park gave the Allies about a month's notice of an Italian declaration of war.

[1] The Battle of France was nearing its final phase when intelligence reports suggested that Italy was on the brink of entering the war on the side of her Axis partner, Germany.

Armstrong Whitworth Whitley bombers could reach their targets from the Channel Islands, while the shorter-ranged Vickers Wellingtons would have to refuel in the south of France.

[3] The Chief of the Air Staff, Cyril Newall noted that the servicing units needed by aircraft reinforcements from Britain to counter the German offensive anticipated in early June were reserved for Haddock, waiting to attack Italy the moment war was declared.

Several bombers hit Geneva and Lausanne in Switzerland, 115 mi (185 km) from their targets, killing four civilians and wounding another eighty.

The Chief of the Air Staff, Cyril Newall, gave an indication of British priorities when he claimed that the servicing units in France needed by any aircraft reinforcements were already committed to Haddock.