The Philadelphia Eagles dealt quarterback Donovan McNabb to their NFC East rivals, the Washington Redskins.
Here are some other notable trades between rivals:
Major League Baseball
December 10, 1984 -- Gary Carter from Montreal to New York Mets: The Mets acquired Carter from fellow NL East members Montreal for four players, Hubie Brooks, Mike Fitzgerald, Herm Winningham and Floyd Youmans.
June 15, 1983 -- Keith Hernandez from St. Louis to New York Mets: Four months before the Carter deal, the Mets obtained Hernandez from then NL East-rival St. Louis for pitchers Neil Allen and Rick Ownbey.
March 22, 1972 -- Sparky Lyle from Boston to New York Yankees: The Red Sox sent the future Cy Young Award winner to their AL East rival in exchange for infielder Danny Cater and a player to be named later.
June 15, 1964 -- Lou Brock from Chicago to St. Louis: The Cards acquired the future Hall of Famer (plus two other players, Jack Spring and Paul Toth) from the arch-rival Cubs in exchange for Ernie Broglio, Doug Clemens and Bobby Shantz.
August 20, 2001 -- Eric Lindros from Philadelphia to New York Rangers: After missing a season due to injury and a contentious contract issue with the Flyers, Lindros was shipped to the Atlantic Division rival Rangers for Kim Johnsson, Jan Hlavac, Pavel Brendl and a third round draft pick in the 2003 draft.
March 23, 1999 -- Chris Chelios from Chicago to Detroit: The Blackhawks traded him to the Red Wings for Anders Eriksson and first round draft picks in 1999 and 2001.
August 9, 1988 -- Wayne Gretzky from Edmonton to Los Angeles: In perhaps the biggest trade in NHL history, the Oilers sent Gretzky, plus Marty McSorley and Mike Krushelnyski to the Smythe Division foe Kings for Jimmy Carson, Martin Gelinas, three first round draft picks and cash.
December 17, 2004 -- Vince Carter from Toronto to New Jersey: Carter changed Atlantic Division clubs as he went from the Raptors to the Nets for Alonzo Mourning, Aaron Williams, Eric Williams and first round draft picks in 2005 and 2006.
October 20, 1976 -- Julius Erving from New York Nets to Philadelphia: Hit hard by their NBA entry fee and territorial damages from the Knicks as part of the NBA-ABA merger, the Nets sold future Hall of Famer Julius Erving to one of their new Atlantic Division rivals, the Philadelphia 76ers. Erving helped the 76ers reach the NBA Finals in 1976-77. The Dr. J-less Nets would finish that season an NBA-worst 22-60.
April 4, 2010 -- Donovan McNabb from Philadelphia to Washington: The veteran quarterback stays in the NFC East, going from the Eagles to the Redskins for a 2010 second-round pick and a third- or fourth-round pick in 2011.
1964 -- Eagles and Redskins swap quarterbacks: The McNabb deal is not the first time there has been a notable quarterback trade between Philadelphia and Washington. In 1964, the teams swapped signal-callers, with future Hall of Famer Sonny Jurgensen going from Philly to D.C. in exchange for Norm Snead. The Eagles also received defensive back Claude Crabb in the deal.
December 1961 -- Bobby Mitchell from Cleveland to Washington: The Browns and Redskins were then both members of the NFL's Eastern Conference. Mitchell, a future Hall of Famer, was dealt by Cleveland, which also had Jim Brown at the time, for Ernie Davis, the top pick in the 1962 NFL draft, then held in December of 1961. Mitchell was the first African-American player acquired by the Redskins and Davis never played a down in the NFL, dying of leukemia in May of 1963.