The first game between the Washington Nationals, (who appeared in the nation's capital out of nowhere in 2005 with no history whatsoever attached to the franchise over thirty-five years after a major league team last called DC its home) and the Baltimore Orioles (who were the Milwaukee Brewers for one year in 1901 then the St. Louis Browns for 52 years (1902-1954) before relocating to Baltimore and becoming the Orioles) took place on May 19th, 2006 in RFK Stadium with the Frank Robinson-led Nats dropping a 5-1 decision to Sam Perlozzo's O's. Robinson's Nationals took the next two with a then-21-year-old Ryan Zimmerman scoring the winning run of Game Two on an errant pickoff throw to third by O's catcher Ramon Hernandez and Livan Hernandez sealing the inaugural series win in Game Three with a 7.0-inning effort in which he held the Orioles to one run in a 3-1 win.
Later in 2006, Washington traveled north to Baltimore where the Nationals dropped two of three in Camden Yards with right-hander John Patterson receiving no support in a 2-1 Game One loss and DC's Flat-Brimmed Closer Chad Cordero giving up the winning run in Game Two when he was brought in for the bottom of the ninth with the score tied at 2-2 and walked the leadoff batter, Luis Matos, who would eventually score on a two-out single by Ramon Hernandez. Series tied, 3-3.
In 2007, the Battle of the Beltway(s) started in D.C. with the Orioles taking two of three "on the road" in Washington. Steve Trachsel took the mound for Baltimore in Game One and bored the Nationals to death outpitched Jason Simontacchi in a game the O's won in spite of two HR's by the Nats' Ryan Zimmerman. Game Two was a 1-1 tie til the top of the 11th when Nats' right-hander Winston Abreu gave up a leadoff walk to Ramon Hernandez, a one-out single to Melvin Mora and a game-winning, two-run RBI double to Jay Payton in what ended up a 3-2 game. The Nationals salvaged a win with Micah Bowie, Billy Traber, Ray King and Jesus Colome putting together a start-by-committee and Chad Cordero earning his 5th save of '07 a half-inning after the Nationals rallied from a 3-1 deficit with a three-run 8th led by Ryan Langerhans RBI single and Nook Logan's game-winning two-run grounder to right. Later that year, June 12-13th, the Nationals swept the last Nats/O's series in RFK to win the season series 4-2 and take a 7-5 lead in the overall battle between the two mid-Atlantic teams.
The teams next met in early 2008, (May 16th-18th), when the Orioles took two of three at home in Baltimore's Orioles Park at Camden Yards. Shawn Hill blew a 3-3 tie in the fifth of the first game, surrendering a leadoff triple to Brian Roberts, RBI double to Melvin Mora and a two-out RBI single to Kevin Millar. Nats' lefty Odalis Perez surrendered 6 runs on 11 hits in 5.0 innings as the Nationals dropped the second game of the series 6-5 in spite of another late eighth-inning rally, and then Washington salvaged the third and final game of the series when Nats' lefty John Lannan outpitched the O's Jeremy Guthrie in a tense 2-1 win. The first time the O's traveled to DC to play the Nats in Nationals Park, June 27-29, 2008, Washington took two of three with Kory Casto's RBI double winning the first game and Ronnie "Walk-Off" Belliard's 2-run 12th inning HR winning the third of three to tie the season series at 3-3 and maintain the Nats' two-win lead in the overall series, 10-8.
A two-run HR by Ryan Zimmerman tied the first game of 2009 between the O's and Nats at 2-2 in the fourth and Nationals' right-hander Jordan Zimmermann handed the ball to the bullpen after 7.0 strong innings only to see Kip Wells finally lose it in the top of the twelfth when Adam Jones doubled in two runs for a 4-2 lead. Ron Villone let the runner he inherited from RHP Julian Tavarez score on a game-winning triple by Aubrey Huff for the O's second-straight win, and the Nats once again salvaged a single win when they rallied from a 5-4 deficit to take an 8-5 lead on the strength of a three-run blast Adam Dunn hit off O's reliever Chris Ray. The '09 season series ended with the Nats again losing two of three, with only John Lannan stopping the bleeding in the third and final game between the teams in 2009, which left the overall series tied at 12-12 heading into this season.
On May 21-23, the O's drove south to Nationals Park to start the 2010 series with their Beltway rivals, dropping two of three on the road to leave the NL East's 3rd place Nats at 23-22 after back-to-back wins. The O's jumped ahead early with 4 runs off Scott Olsen in Game One, then held on for a 5-3 victory decided by another Adam Jones' HR. In the second game a 4-run sixth led by Roger Bernadina, Alberto Gonzalez and Adam Dunn's RBI hits, lifted the Nats to a 7-6 victory closed out by Sean Burnett, Tyler Clippard and Matt Capps. The third game of the series went to the Nationals as well, with Josh Willingham's dramatic 11th inning walk-off HR the difference in a game Matt Capps had blown in the ninth. The 2-1 series win put the Nationals back ahead 14-13 in the overall series with the O's, and tonight the teams renew their (geophrapical, league-mandated, manufactured) rivalry with the first of three in the house that Cal built with J.D. Martin and Jake Arrieta on the mound in Baltimore at 7:05.