Obviously something bad happened at some place called Trafalger two years ago, something called the Twighlight Purchase was involved. I haven't played Secret Ops or read the fiction, though...LOAF? Can we get an answer here?
Hmmm. There's a place in London called Trafalgar Square. The Brits also won a major navy battle at a place called Trafalgar, but that was a heck of a lot more than 2 years ago.
Trafalgar is a star system -- one of the worlds that the Kilrathi tested their biological weapons on in '69. As for what happened in '79... we're never told, that's just flavor text (aside from that whatever it was was called the 'twilight purchase').