The most relevant example I know is the Zimmerman telegram in 1917 which British intelligence decrypted and passed along to Pres Wilson. It detailed plans Germany had made to invade the US with Mexico's help. Wilson released it to newspapers in March as support for his decision to declare war on Germany in April. However the primary justification for war wasn't the telegram, but the public decision by Bismark to fully resume uboat attacks on merchant ships in the Atlantic.
So even as damning and revealing as the Zimmerman telegram was, ultimately it was Germany's bold resumption of the torpedoing of US oceangoing traffic that catalyzed US public opinion into ending 3 years of American neutrality and joining the fight in WWI. Thus even when intel is most damning, the role of intel will always be subservient to publicly motivating events like lost lives, as in the much ballyhooed sinking of the Lusitania 2 years before (1915).
Wikipedia has a couple of outstanding articles on the topic:
So even as damning and revealing as the Zimmerman telegram was, ultimately it was Germany's bold resumption of the torpedoing of US oceangoing traffic that catalyzed US public opinion into ending 3 years of American neutrality and joining the fight in WWI. Thus even when intel is most damning, the role of intel will always be subservient to publicly motivating events like lost lives, as in the much ballyhooed sinking of the Lusitania 2 years before (1915).
Wikipedia has a couple of outstanding articles on the topic:
https://en.m.wikipedia.org/wiki/Zimmermann_Telegram
https://en.m.wikipedia.org/wiki/American_entry_into_World_Wa...