British spies considered a plan to bring out Adolf Hitler's softer side by secretly adding female hormones to Der Fuhrer's food, according to a new book.

The idea that Hitler's violent quest for world domination could be subdued with steady doses of estrogen was one of the bizarre cloak-and-dagger plots dreamt up to outmaneuver Nazi Germany, according to a new book Secret Weapons: Technology, Science And The Race To Win World War II by British professor Brian Ford.

"There was an Allied plan that they would smuggle estrogen into Hitler's food and change his sex so he would become more feminine and less aggressive," Ford of Cardiff University told The Telegraph.

"Their research had showed the importance of sex hormones - they were beginning to be used in sex therapy in London," Ford said to the newspaper.

The gambit was favored over an outright poisoning, because estrogen is tasteless and its effects wouldn't be immediately detected, Metro reported. But the feminizing plan never made it beyond the drawing board.

The agents allegedly conjured up a bevy of options to win the war that seem far-fetched now, according to Ford. Other ideas called for dumping glue on Nazi soldiers to trap them, disguising explosives in the fruit tins that Germany imported and releasing poisonous snakes on enemy lines.

Ford uncovered the scheme while looking through stacks of recently declassified files from World War II, according to the ABC, the Australian news agency.

The estrogen plot is almost as bizarre as Hitler's attempt to give soldiers blow up sex dolls to avoid syphilis and build up an army of dogs that could read, talk and spell.