The Colts and Rams franchises will always be linked thanks to a bizarre owners' swap 45 years ago.
If you're unfamiliar with the story, the late Robert Irsay, then a multi-millionaire heating and cooling contractor, purchased the Los Angeles Rams with a bid of $19 million in July of 1972. After that transaction was completed, Irsay traded the Rams to Colts' owner Carroll Rosenbloom for his Baltimore franchise... all in the same day!
The details of the swap are in this Chicago Tribune article.
Irsay's motivation for trading for the Colts instead of keeping the Rams? Johnny Unitas. He's quoted in the Tribune article calling Unitas "one of the best people in the world".
Unfortunately for the Colts, they immediately went into the tank under Irsay's watch. After winning three NFL championships and three more conference titles as one of the league's best franchises from 1958-71, Irsay's Colts went 11-33 in his first three seasons and never won another playoff game in Baltimore. In fact, they won only two playoff games while Irsay was owner - both in 1995 in Indianapolis - before his death in 1997.
Meanwhile, Rosenbloom's Rams took off. They made the postseason in six of his seven seasons as owner, including a run of six-straight NFC West championships. He tragically drowned at the age of 72 prior to the 1979 season.