July 3, 1940. After only 54 days into office, British Prime Minister Winston Churchill ordered his Navy to take control of French ships, or destroy them if the French refused to relinquish control. What led to this unprecedented and controversial attack was a dramatic series of events that saw France being overrun by the Nazis in a matter of weeks, Roosevelt fearing that Britain would fall just as quickly, and Churchill needing a way to prove otherwise.

THIRTEEN’s Secrets of the Dead explores the dark side of Britain’s fight against the Nazis in Churchill’s Deadly Decision, premiering nationally on Wednesday, May 12, 2010 at 8 p.m. (ET) on PBS (check local listings). With eye-witness accounts and testimonies from British and French sailors who were involved in the attack, recently unclassified documents between Churchill and Roosevelt, and actual notes from British War Cabinet meetings, the film takes viewers through the harrowing chain of events that led up to the attack, and into the crucial hours during which it actually took place. Actor Liev Schreiber (Taking Woodstock and X-Men Origins: Wolverine) narrates.

Preview this episode:

“This is one of the long-forgotten stories of World War II, and one that was ultimately integral to America’s involvement into the war,” says Jared Lipworth, executive producer of Secrets of the Dead. “It solidified the relationship between Churchill and Roosevelt, but was also a classic example of the difficult—and deadly—moral decisions that leaders often have to make during wartime.”

The situation began when the French, despite assurances to their British allies that they would never capitulate to the Nazis without British approval, signed an armistice with the Germans. As part of that deal, the French agreed to recall their Navy to French ports, where the ships would remain for the duration of the war. Churchill, worried that one of the world’s great navies would end up in German hands, asked the French to turn the ships over to the British instead. The French refused, but Admiral Darlan, commander of the French fleet, swore that he would sink his own ships if the Germans ever tried to take control.

Meanwhile, Churchill had been trying to convince Roosevelt to give the British 50 old American warships, which they could use to defend themselves against the inevitable Nazi attack on the United Kingdom. But Roosevelt, fearing that the green British Prime Minister didn’t have the backbone to stand up to the Germans, worried that his ships would just end up in German hands when Britain fell.

Backed into a corner and not trusting the French admiral to live up to his promise, Churchill took matters into his own hands. He launched Operation Catapult to capture the French Fleet before it returned to French waters. A number of the most powerful French battleships were docked at a naval base in the French-Algiers port of Mers-el-Kebir. Churchill issued the French an ultimatum: Give up the vessels to the British, sail them to Allied ports, or face attack from the Royal Navy.

The French stalled, hoping for the arrival of reinforcements. The deadline passed, and the British attacked with devastating force, destroying a number of French ships and killing 1,300 French sailors—more than the number of French soldiers killed by the Germans at that point in the war.

France declared the action a horrific act of mass murder. Germany used it to release anti-Britain propaganda in Europe. Britain stood firmly by its leader and supported Churchill’s decision. But most importantly, Roosevelt saw the attack as a confirmation of British resolve, and soon supplied Britain with the 50 destroyers it so desperately needed.

Secrets of the Dead: Churchill’s Deadly Decision was produced by Furnace Limited for THIRTEEN in association with WNET.ORG, Channel 4, National Geographic Channel UK, ABC Australia, and ZDF. Richard Bond is writer/director. Phil Craig is executive producer for Furnace. At THIRTEEN, Jared Lipworth is executive producer. William R. Grant is executive-in-charge.