Exercise Fabius 2-7 May 1944 was, arguably, the largest training exercise to take place in the UK. It would be the final rehearsal for Operation Overlord . It was a rehearsal of the landings on the four invasion beaches in the Normandy coast between the rivers Orne and Dives; ( Sword, Juno, Gold and Omaha beaches) .
Utah beach, geographically separated from the other four beaches was considered a separate assault from naval point of view. The rehearsal for the landing on Utah Beach was Exercise Tiger and took place on 26-30 April on Slapton Sands in Devon.
Ex Fabius allowed participants the chance to rehearse under conditions as close as possible to those they would face. It also allowed the ports to practice supporting a large scale landing. This was a dress rehearsal with the landing forces approaching the beaches behind mine sweepers and landing craft lowered ten miles off shore. The landings were accompanied by live firing from ships.
The assault troops for each of the D Day beaches would practice landing on a stretch of coast with a similar configuration to that they would face on D Day. The exercise was too close to D Day for any further experimentation or changes to the plan. Some units would not return to their previous accommodation, but instread to their assault assembly area.
3rd British Infantry Division was assigned to assault Sword beach with the town of Ouistrhem and the River Orne on their left flank and the city of Caen as its objective. On Exercise Fabius it landed near Littlehampton with the River Arun on its Left and Arundel its objective.
Robin Dunn, who was Battery Commander of 16 Battery of 7 Field Regiment claimed post war that there were problems which were identified and if put right would have enabled the allies to do better on D Day.
” While at Bolney we had our final rehearsal of the invasion on the south coast near Arundel……..We had a new divisional commander, Tom Rennie, who had commanded a brigade of 5lst Highland Division with distinction in 8th Army and had a high reputation. The commander of 185th Brigade was Brigadier K. R Smith, who had been with the brigade for some time and had so far in the war seen no action. He was a good trainer of troops who had worked us hard during our training in Scotland. But he did not fully accept the role of the brigade in the divisional plan. We had heard that 21st Panzer Division had been identified as having recently arrived about thirty miles inland of our landing beach. The presence of this division became a fixation in K.P.’s mind. He was haunted by the idea that, if 185th Brigade pushed too boldly inland, 2lst Panzer would come round our right flank, which was in open country and cut us off from the beaches. There was wooded country on the left and KP. wished to infiltrate his infantry through the woods beside the river and approach the objective in that way along the divisional left flank. During our final rehearsal he attempted this manoeuvre, which involved keeping one battalion on our original thrust line and passing the other two round their left flank in a wide turning movement. The result was chaos. The battalions became separated from one another and the Brigadier lost communication with the flanking force which lost all momentum. I was at brigade HQ when Tom Rennie arrived and said wearily, ‘You won’t let this happen on the day will you KP? It would have been better, even at that late stage, if he had sacked KP. on the spot.” Robn Dunn Sword and Wig.
Although many fewer than on Ex Tiger, there were casualties on Exercise Fabius. On the Morning of 4 May twin engine fighter bomber aircraft of Coastal Command attached Allied motor boats inflicting many casualties. Possibly the German attack on Ex Tiger had made the airmen a little trigger happy.
Places associated with the story of the training and rehearsals for D day can be found across Britain, from the sections of Atlantic Wall built in Scotland to the beaches which stood in for the Norman Coast.