When he spoke on the phone to Gordon Brown, the prime minister was sitting in his war room in Downing Street with Peter Mandelson, once a close friend, then an arch enemy and now amazingly transformed into his most crucial ally. (theguardian.com)
The original cracking of the Enigma code was an early and crucial Allied triumph in WW II. (discovermagazine.com)
After John Kelly came in as chief of staff last summer, Porter ended up serving as a crucial ally in Kelly's effort to install a more rigorous process. (vox.com)