At the beginning of the War the codebreakers were unable to cope with the amount of material and the Forces were reluctant to trust the information. By 1941 Bletchley Park (Ultra) played a significant part in land war campaigns against Rommel. The Navy were able to supply Ultra with necessary information concerning the Atlantic.
Colossus generated the complete German order of battle for D-Day and the reaction to British tactics.
However, it was vital that the Germans never discovered that Enigma was broken and the Forces could not act upon information until the enemy felt it had come from other sources.Though the Germans adpated Enigma, Bletchley Park still kept up and provided Allied forces with an abundance of information.
It is believed that Ultra shortened the War by 2 years and saved countless lives.