This was an Allied deception plan to suggest that Lieutenant General Sir Oliver Leese’s British 8th Army was preparing to undertake a major advance to the north along the east coast of Italy with the aid of an amphibious landing near Pescara (January/February 1944).
The object of the undertaking was to persuade the Germans not to transfer any major formations of Generloberst Heinrich-Gottfried von Vietinghoff-Scheel’s 10th Army from the Italian eastern littoral area westward to reinforce the formations facing the Allies near the west coast at Cassino and Anzio.
'Clairvale' was the first of a series of operational-level deceptions undertaken in Italy in parallel with 'Zeppelin' (i), and can in some respects been regarded as a successor to 'Chettyford'. The undertaking was based on the 'story' that Lieutenant General E. L. M. Burns’s Canadian I Corps on the 8th Army’s right wing would drive to the north along the Adriatic coastal road aided, as noted above, by a landing at Pescara. Implemented largely by highly visible activities at Termoli, the base from which the Pescara landing was notionally be launched, 'Clairvale' ran through a time late in January and much of February, by which time General the Hon. Sir Harold Alexander had brought to an end the efforts of his Allied Forces in Italy command at Cassino with the conclusion of 'Avenger', otherwise the 2nd Battle of Cassino, on 15 February.