Why didn't the British ministry of magic call upon their foreign counterparts for aid in the war against Voldemort, I mean if they had the help from one other country they could gain the upper hand way quicker just through sheer numbers.
1 Answer
For quite a while the Ministry wouldn't even admit there was a problem (reference: from the tail end of Goblet of Fire to the tail end of the Order of the Phoenix), and Scrimgeour (speculation warning) probably thought himself capable of handling the job.
By the time it was obvious that it was too big for the natives to handle, it was too late to call for help.