The German trap that Schofield and Blake were trying to prevent was a fake German withdrawal that would have lured the British to attack. The Germans would then slaughter them en masse.
The Germans wanted the British to attack and the casualties on the British side would have been heavy.
Schofield and Blake were told to go deliver a message to a British colonel about a German ploy to inflict heavy losses on the British.
The German plan was to retreat which would lead the British to believe that they were winning the battle. The Germans would then counterattack and kill a lot of British soldiers.
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