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Is Pressure a true story? Here’s the real history behind the D-Day drama
Fact and fiction blast into cinemas with Pressure, a gripping drama that focuses on the immediate buildup to Operation Overlord. Jonathan Wright unpicks the true story of the tense hours when meteorologists clashed over whether a storm was going to hit Normandy in early June 1944
- Jonathan Wright
Published: May 29, 2026 at 6:00 PM
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Anthony Maras’ Second World War movie Pressure – adapted for the screen from David Haig’s hit play – takes us into the heart of a military storm. We join the action in late spring 1944 at Southwick House, five miles north of the naval port of Portsmouth on England’s south coast, where planning for the Allied invasion of occupied France is at an advanced stage.
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Enter Group Captain James Stagg of the Royal Air Force, a meteorologist later described by Dwight D Eisenhower, supreme commander of the Allied Expeditionary Force, as a “dour but canny Scot”.
Stagg is spiky, difficult, a stickler for detail. He’s also convinced that, despite the weather in May having been largely fine, a storm is brewing in the Atlantic. His American counterpart, Irving P Krick, vehemently disagrees. But both men cannot be correct…
Is Pressure a true story?
Yes – Pressure is based closely on the true story. Weather was of crucial importance to those planning the D-Day landings. Ideally, Eisenhower and his senior officers wanted the invading flotilla to set out on a night with minimal cloud cover just before or soon after a late-rising full moon, so that Allied airmen and sailors would have enough light to see their way.
In addition, the Allies wanted to land shortly before dawn on a rising spring tide. That would allow them to see obstacles on the Normandy beaches and landing craft to be run aground and unloaded without becoming stranded as the sea retreated. But the more prescriptive the demands for specific conditions, the fewer dates would be acceptable.
Troops splash ashore in a scene from Pressure, Anthony Maras’ film about decisions leading up to D-Day in 1944 | Credit: Alex Bailey/Focus Features/ STUDIOCANAL © 2026 All Rights Reserved
In mid-May, Eisenhower selected Monday 5 June as D-Day – if the weather looked likely to be suitable. If, though, conditions were too choppy and seas too high, there was a risk that landing craft would sink and men would drown. The world’s largest-ever seaborne invasion might then end in disaster.
This level of caution by Eisenhower and the Allied high command was born of bitter experience. A raid on the German-occupied French port of Dieppe in August 1942 had been a disaster: the predominantly Canadian assault force fought valiantly, but this full-frontal attack on a heavily defended port had been folly.
Similarly, an amphibious landing at Anzio in Italy in January 1944, Operation Shingle, failed to capitalise on the element of surprise. Allied troops were stymied by a combination of German resistance and marshy terrain that favoured the defending forces.
Yet there were risks in delaying the launch of Operation Overlord, too. What if the enemy realised that the Allies were planning to land in Normandy rather than in the Pas-de-Calais region, as the German high command expected?
As the potential threat of stormy weather grew, Pressure suggests, James Stagg was called on to advise whether the operation was safe to go ahead. Stagg, portrayed as a man who took decisions based on the interpretation of data, urged caution. But he faced opposition from his American counterpart Irving P Krick, a brash meteorologist who based his forecasts on historical weather patterns.
What’s the real history behind Pressure?
Much of what we see on the screen is broadly true. Those charged with authorising the invasion were faced with decisions that would have made many quail.
Pressure also captures the characters of key players at Southwick House. As played by Damian Lewis, for instance, General Bernard Montgomery – by that time, commander of Allied Ground Forces – is gung-ho, blasé about landing as planned on 5 June whatever the risks. There’s truth in this portrayal of a man who, for all his brilliance, could be high-handed and often exasperated his fellow senior officers, including Eisenhower.
British General Bernard Montgomery (played in Pressure by Damian Lewis) advocated launching Operation Overlord on 5 June even in adverse weather conditions | Credit: Focus Features/STUDIOCANAL © 2026 All Rights Reserved
As for the central tension in Pressure, the taciturn Stagg and the expansive Krick certainly didn’t see eye to eye. Moreover, the suggestion that Krick was regarded as flashy – even a charlatan – by contemporaries is as rooted in reality as the notion that people found Stagg to be hard work. Francis Reichelderfer, director of the US Weather Service, reportedly thought Krick a smug, supremely self-confident self-promoter.
However, we shouldn’t forget that this is at its heart a screen drama. The script, co-written by Haig and director Anthony Maras, makes much of those meteorologists’ disagreements. Their clashes come to represent the idea of – to employ a phrase attributed to both Oscar Wilde and George Bernard Shaw – nations divided by a common language.
British meteorologist James Stagg (Andrew Scott) clashes with American counterpart Irving P Krick (Chris Messina) in Pressure | Credit: Alex Bailey/Focus Features/ STUDIOCANAL © 2026 All Rights Reserved
In truth, they were just two of the meteorologists working across three different teams from the United States Strategic Air Forces in Europe, the Meteorological Office and the Royal Navy Meteorological Service, all reporting to Supreme Headquarters Allied Expeditionary Force.
In many respects, Stagg’s job was to act as a referee and, where the experts couldn’t agree, to decide what information should be laid before the top brass. It’s a strange detail that Stagg – a geophysicist whose primary interest in the interwar years was in terrestrial magnetism – wasn’t the most highly regarded meteorologist of those who worked on the D-Day forecasts. The Norwegian Sverre Petterssen, for example, was far more eminent, and a key figure shaping the forecast that pushed the invasion back by a day from the originally planned date, 5 June.
However, like Eisenhower, Stagg understood committee work and administration. He may have found social interactions difficult, but he ultimately arrived at the correct forecast, enabling the D-Day invasion force to land on Tuesday 6 June.
If you want to get closer to some of the original sources, in this video, Charlotte Vosper travels to the UK MET Office to explore more of the real history behind Pressure. You'll see a personal diary from Group Captain James Stagg, the meteorologist (played in the film by Andrew Scott) who was tasked with providing crucial weather charts that helped make the final decision.
Did the Associated Press (AP) mistakenly announce an invasion, as Pressure suggests?
Yes. On Saturday 3 June, an AP flash – sent out accidentally by an inexperienced London telegraph operator – did state that “Eisenhower’s forces are landing in France,” only to have to cancel the report.
Did the Allies use inflatable tanks as a decoy?
Yes. Inflatable tanks were deployed in south-eastern England to fool the Germans into believing that Allied forces were preparing to invade the Pas-de-Calais coast, rather than the actual beaches targeted farther west in Normandy.
Decoy inflatable tanks were produced to fool the Germans into thinking an Allied invasion of France would attack the Pas-de-Calais coast | Credit: Getty Images
More generally, the Allies went to huge lengths to convince the Germans that an imaginary US Army Group was based in south-east England. Winston Churchill, as well as many in the British military and intelligence services, had a real enthusiasm for such wizard wheezes.
Was D-Day rehearsal Exercise Tiger really a disaster, as depicted in Pressure?
Yes. In April 1944, preparing for the expedition planned to attack Utah Beach, US troops undertook a rehearsal landing at Slapton Sands in south Devon, Exercise Tiger. Eisenhower specified that live rounds were to be fired over the heads of the troops to acclimatise the men to what it would be like to wade ashore in France. For similar reasons, naval forces were to bombard the land 50 minutes before the men landed.
But there was a miscommunication and, although the exercise had been delayed, some of the landing craft did not receive word of this change – so the troops landing came under direct fire from the sea. Compounding the misery, there were also heavy losses when fast-moving German E-boats ambushed a convoy of landing ships in Lyme Bay.
Allied commander General Dwight D Eisenhower (Brendan Fraser) was shaken by the fatal errors during the D-Day rehearsal Exercise Tiger in Devon | Credit: Alex Bailey/Focus Features/ STUDIOCANAL © 2026 All Rights Reserved
The official death toll from these disasters stands at 749. With D-Day imminent, the incident was covered up.
Were weather reports from Ireland crucial to the final forecast?
Yes. On 3 June, a report of force six winds and barometer readings of rapidly falling air pressure, recorded at Blacksod Point weather station in County Mayo, was sent to Britain by post office clerk Maureen Flavin. This suggested that a storm was approaching – leading to the postponement of the invasion for 24 hours. Nevertheless, Stagg believed that a ridge of high pressure was building up from the Azores, indicating that better weather would follow.
Blacksod Lighthouse in County Mayo, Ireland, site of the weather station where Maureen Flavin took readings that informed the timing of D-Day | Credit: Alamy
He was right. On 4 June, Maureen’s future husband, lighthouse keeper Ted Sweeney, reported: “Heavy rain and drizzle cleared, cloud at 900 feet, and visibility on land and sea very clear.”
D-Day was on.
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Pressure is in UK cinemas from Wednesday 9 September
Authors
Jonathan Wright
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