Operation Glimmer - Background

Background

Glimmer, Taxable and Big Drum were conducted as part of Operation Bodyguard, a broad strategic military deception intended to confuse the Axis high command as to Allied intentions during the lead-up to the Normandy landings. The London Controlling Section (LCS) had spent some time convincing Germans that the First United States Army Group (FUSAG) represented the bulk of the Allied invasion force. FUSAG, however, was entirely fictional – its existence fabricated through Operation Fortitude South.

The Allied story for FUSAG was that the army group, based in south-east England, would invade the Pas de Calais region, probably several weeks after a smaller diversionary landing in Normandy. As D-Day approached, the LCS moved on to planning tactical deceptions to help cover the progress of the real invasion forces. As well as naval operations, the LCS also planned operations involving paratroopers and ground deceptions. The latter would come into effect once landings were made, but the former (involving naval, air and special forces units) were used to cover the approach of the true invasion fleet.

In preparation for the coming landings, Allied scientists had worked on a number of techniques for obscuring the size and disposition of an invasion force. For example, radar jamming using wireless sets and chaff (known by the codename Window). Allied command decided that, rather than mask the approaching fleet, these measures would serve to alert German defenses. Instead it was decided to combine these techniques with small groups of boats to simulate an entire invasion fleet aimed at the Calais region – Operations Taxable and Glimmer – playing on the FUSAG story. The chaff and other countermeasures would hide the small size of the naval force, and wireless traffic would mislead the Germans into expecting a major landing.

It was also decided that another deceptive force would use radar counter measures on the western flank of the true invasion fleet. Operation Big Drum was intended to lend confusion as to the extent of the landings in Normandy.