Jackson threw 41 of his 71 pitches over four innings for strikes, but allowed 11 baserunners to reach. All in all, Jackson ended the day allowing four runs on seven hits and three walks while striking out three.
The Tigers broke the game open in the fifth, when they scored five runs with the help of shaky defense by the Nationals.
Bryce Harper struck out in his first four at-bats before getting a double in his final at-bat in the ninth. He was optioned to AAA Syracuse following the game and will not appear on the Opening Day roster.
The Nationals are off on Monday and will return to action on Tuesday when they take on the New York Mets.