the computer used was essintial to it, they had the machine but didnt know the settings, the computer used the enigma algorythem to try to crack the wheel settings for that day do using an enigma machine (or an imitation) the message could be decrypted.
Its an old quote to pull up but oh well. The brits did invent the 1st computer, it was used in th second world war to crack german enigma. The reason the US is written to have the first computer is because the british computer was protected under the 50 year secret act so it couldnt be announced that "we beat you to it" when the US got the idea to make one.