From The Sun (UK):
British and French nuclear submarines which collided deep under the Atlantic could have sunk or released deadly radioactivity, it emerged last night. The Royal Navy’s HMS Vanguard and the French Navy’s Le
Triomphant are both nuclear powered and were carrying nuke missiles.
[...]The collision is believed to have taken place on February 3 or 4, in mid-Atlantic. Both subs were submerged and on separate missions.
She (Vanguard - ed.) was last night towed into Faslane in Scotland, with dents and scrapes visible on her hull. Triomphant limped to Brest with extensive damage to her sonar dome.
Triomphant has a crew of 101. Vanguard weighs 16,000 tons, is 150 metres long and has a crew of 140.
No word yet on whether the French boat surrendered.
Apparently, there were a number of collisions between US and Russian boats during the Cold War. At least one may have resulted in loss of a Russian boat and its crew. These guys, however, were (reportedly) not playing chicken and just ran into each other in the middle of the ocean. I'm not sure I believe that...