LONDON — A ship I once served in had a small brass plate on the bridge with a quotation from Thucydides, the Greek statesman, historian and seaman of the fourth century B.C.: "A collision at sea can ruin your whole day." It is still true.
It is harder to collide at sea than on land, since there are no blind curves and nothing moves much faster than a bicycle, so my normal reaction to a collision at sea is to think "How can they have been so stupid?" But here is a collision that beggars the imagination.
In the North Atlantic Ocean, on the night of Feb. 3-4, at an undisclosed depth, the British nuclear submarine Vanguard and the French nuclear submarine Le Triomphant ran into each other. Both boats were "boomers," missile-firing submarines carrying 16 ballistic missiles, each of which can deliver several nuclear warheads at intercontinental range.