On June 24, Churchill’s War Cabinet met three times, dominated by what Sir Alexander Cadogan called “the awful problem of the French fleet.” The newly revealed French armistice terms said Germany would occupy much of France while a nominally free government ruled from Vichy, and Article 8 stated that Germany had no intention of using the French fleet except for limited purposes. Churchill did not believe this assurance, seeing vague phrases such as “coast surveillance” and “minesweeping” as loopholes that could let Hitler use the ships against Britain. Despite repeated meetings, the cabinet failed to settle on a final response.

Just after the last meeting ended at 1:15 a.m. on Tuesday, London heard its first “red warning” air-raid alert since the war began. The sirens signaled an imminent attack, but no bombers arrived, because a civilian aircraft had triggered the alarm. The false alert still exposed public unease: Olivia Cockett recorded the tense stillness in her home, and Home Intelligence found that many Londoners had not heard the warning or had chosen not to wake their children.

By June 28, Churchill received another disturbing report from Dr. Jones of Air Intelligence. Using information from Bletchley Park, disguised as an “unimpeachable source,” Jones reported that Flakkorps I had requested 1,100 maps of England, a practical sign that Germany might be preparing to land anti-aircraft units in England and Ireland to support an invasion. Churchill treated this as concrete evidence that the next three months would be the most dangerous period, before worsening weather reduced the invasion threat.

Because Churchill believed invasion might be close, his orders became more urgent and specific. He told Pug Ismay to arrange trenches across long open fields within forty-eight hours to obstruct tanks and troop-carrying aircraft, and he ordered studies of tides and moon phases to identify when seaborne landings would be easiest. Churchill also asked whether mustard gas could be used to drench beaches and enemy lodgments if German forces landed, reasoning that Britain should not wait for the enemy to use such methods first. He also worried about parachutists and fifth columnists landing in disguise, especially in British uniforms.

The strain of the crisis was affecting Churchill personally. Clementine Churchill wrote to warn him that his rough, sarcastic, overbearing manner was alienating colleagues, subordinates, and secretaries, and that wartime pressure did not excuse behavior that suppressed honest advice. She urged him to lead with calm and kindness. Yet when John Colville saw Churchill the next morning, he found him outwardly serene in bed in a red dressing gown, dictating papers with his cat Nelson nearby, an image of composure that contrasted with the pressures surrounding him.