Brian Schneider, who went into the game hitting .293 (17-for-58) in May after a .184 April, and Ryan Zimmerman also hit home runs to help Washington set a single-game season high in runs for the second consecutive game. The Nats scored 27 runs for the first three games of the four-game series, the most the club has scored in any set of three games this season. Their previous high was 19 in a three-game sweep of Florida on May 11-13.
"Some of those balls were hit pretty hard, regardless of where you are," manager Manny Acta said. "You really need offense to win in this place, unless you have a big-time guy on the mound."
The 12 runs were the most by the Nationals since they scored the same number in a 12-8 win at Houston on April 8, 2006.
Washington needed fewer than five full innings to pile up nine hits and seven runs against Cincinnati right-hander Kyle Lohse, making it easier for Jason Simontacchi to improve to 2-2. The right-hander allowed four hits and a run with three walks and four strikeouts in 5 2/3 innings. He threw 91 pitches.
"You're aware of how the ball gets out the yard here, but you don't change your approach," Simontacchi said. "Ground balls can't get out. It's a matter of working your pitches inside and outside and keeping them off-balance."
Church, in the first plate appearance of his first start after missing the last two with an injury to his left forearm, gave Washington a 2-0 lead in the first inning with a two-out, two-run homer to right-center field. The homer was Church's fourth of the season and first since April 14, when he hit one off Mets right-hander Orlando Hernandez at New York.
"Everybody knows what it's like coming in," Church said. "That's why I hated missing the first two days here. We're just taking advantage."
"It was a good day for him after a couple of days off," Acta said. "It shows he's fine."
Simontacchi allowed a home run by Ryan Freel to lead off the bottom of the first inning, but the Nationals got it right back in the top of the second. Brian Schneider doubled with one out and tried going to third on Nook Logan's grounder to shortstop Alex Gonzalez, whose throw to third was ruled to have hit Schneider for a throwing error that allowed the Washington catcher to score.
The Nationals broke the game open with a three-run fourth. Austin Kearns scored from first base on Dmitri Young's double to the left-center-field warning track and Schneider, who went into the game hitting .364 (12-for-33) in his last nine road games, followed with his second home run of the season and first since April 18 off Philadelphia right-hander Adam Eaton.
"We're getting some timely hits and starting to feel better," Schneider said. "This is a great ballpark to hit in, but you've still got to hit the ball hard."
"We need his bat in the bottom of the lineup," Acta said.
Cristian Guzman tripled and scored on a wild pitch in the fifth, and Zimmerman and Church teamed up in the seventh on Washington's first back-to-back home runs of the season.
Ray King was ejected by plate umpire Lance Barksdale after King walked in a run during Cincinnati's four-run seventh.
Church set his career high in RBIs with a three-run double in the eighth.
The three-hour, 38-minute time of the game was the longest for Washington in nine innings this season. The previous longest for the Nationals was 3:10 on April 17 in a 6-4 loss to Atlanta.