"They threw everything on me," Hammel said. "When you do those little mosh pits, those celebrations, guys bring everything to the table. You never know."
Hammel improved his record to 5-2 on the season with the win and lowered his ERA to 2.76. His ERA over his previous five starts is 1.74.
"Jason Hammel was outstanding," manager Joe Maddon said. "How many games in a row is that? You talk about pitching at an All-Star quality or level, he has. He's been unbelievably good, consistent, deep into the game, strike thrower. Just outstanding."
For six innings, the Nationals could only manage two hits off the Cubs' starter. Bryce Harper flared a single to left field in the first, and Wilson Ramos smashed a home run in the second.
Clint Robinson worked an infield single in the seventh with two outs to end that run, and Danny Espinosa led off the eighth with a double. Neither saw third base.
"I was battling," Hammel said. "Definitely didn't have the best fastball command today. But I was able to throw the slider for strikes, so they have to honor that and I made big pitches, and [my team made] great defensive plays all over the place."
The starter hit for himself in the eighth and returned to the mound in the ninth, trying to notch his first complete game since 2012.
Harper's solo shot to left-center to lead off the ninth cut the Cubs' lead to 4-2 and ended that plan.
"I wanted to finish that one bad," Hammel said. "I had pitched Bryce well all day and over our challenges in our careers against each other. Shoulda, woulda, coulda, I guess. But I wish I would've thrown a different pitch."
Pedro Strop recorded the final three outs, and Hammel improved to 9-0 versus the Nationals in his career. The secret behind that that, well: "If I told you, I'd have to kill you," Hammel said. "Some places you do better than others, I guess. I do love to pitch in this stadium. It's comfortable. It's a good atmosphere."
Jacob Emert is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.