The green flag flew over the historic Milwaukee Mile, and polesitter Josef Newgarden wasted no time in putting some space between himself and Ryan Briscoe and the rest of the field.
Helio Castroneves, after missing qualifying, began his storm to the front from the very back of the grid.
Newgarden led Briscoe and Tony Kanaan around the mile-long short oval through the early stages of the race. The three came tighter together as Briscoe caught the young American as the frontrunners caught the backmarkers and began working their way through the traffic.
The first round of green flag pit stops got underway at Lap 51, and was kicked off by Castroneves from the back of the pack. The field then took one-by-one to the pits for service. The only mishaps on this round of stops were experienced by Ryan Briscoe and Graham Rahal. Briscoe's crew had troubles putting the air jack in, costing well over 10-seconds extra. Rahal had a similar problem, and it cost him valuable seconds as well. As he pulled back onto the track, Rahal stated over the radio: "We just killed ourselves, guys."
His crew encouraged him, told him to get going, and racing got back underway as normal.
Newgarden continued his campaign at the front - even more comfortably than before after Briscoe's issues on pit lane. Before the second round of pit stops began just after Lap 100, Newgarden had led all but five laps.
Briscoe was again plagued by difficulty during his pit stop as his fuel man had trouble getting the hose back out of the No. 5 Schmidt Peterson Motorsports Honda-powered car. Other than this second unfortunate mishap for Briscoe, this second round of stops was more uneventful.
The first yellow flag of the race came out on Lap 116 after a serious mechanical issue for James Jakes. After starting from an impressive fifth on the grid, Jakes suffered a blown engine, joining Pippa Mann as the second car to retire from the race - both Hondas.
Under yellow, Josef Newgarden dropped to 11th after having his own mishaps in his pit box.
The 250-lap event went back to green on Lap 130, just past the halfway point, on a second attempt after leader Sebastien Bourdais jumped the start a bit - per Race Control.
The race went almost immediately back to yellow after a big crash between Briscoe and reigning series champion to Will Power.
Briscoe got loose on Lap 132, spun, collected the Australian, and sent them both hard into the outside wall. Power's No. 1 Penske Chevrolet sustained rather heavy damage, and the race came to an end for Briscoe and himself.
As the race got back underway on Lap 142, three Hondas and one Chevrolet out, hectic racing returned throughout the pack as Bourdais, Kanaan, and Newgarden ran at the front in the top-three.
The field got back into comfortable single-file racing, spread out a bit, and Newgarden got by the Brazilian for second.
At Lap 157, the next retirement from the race took place. While Bourdais was dominating with great pace at the front, his KV Racing Technology teammate Stefano Coletti suffered a blown engine and his day came to a sudden end. His team commended his effort in the first 150 laps of the race as he exited the track and came down pit lane.
Green flag pit stops took place once again, and young American driver of the young American team CFH Racing, Josef Newgarden, returned to the lead. Closely behind ran Kanaan and Bourdais was pushing hard from fifth position as more pit stops were set to take place.
Entering the final 35 laps, Bourdais had lapped every single other car on track before making his final stop of the race. At that stage, everyone else was saving fuel and he had fresh tires; he had the clear advantage in these late stages of the race.
Also notable from this point in the 250-mile event was that Castroneves had advanced to second position, just two seconds behind leader Bourdais.
With 30 to go, Bourdais jumped back out to a five second lead over Tony Kanaan, who had taken over second from Castroneves.
At Lap 223 of 250, Justin Wilson was stopped on track after a very long pit stop that saw troubles with an air-gun - bringing out the second caution of the race. Wilson, in his first race with Andretti Autosport since Indianapolis after it was announced that he would join the team for the remainder of the season.
The pits opened, and the majority of the field came in and out. Rahal advanced to second, up to spots from where he was before the stop, and Castroneves inherited the lead.
Bourdais led with 10 to go, and was being chased by Castroneves and Rahal - all equally spaced out.
With three to go, Bourdais, having led 115 of 250 laps, had a very comfortable lead over Castroneves and Rahal. He took the white flag, embarking on his final lap at the famed track that has seen racing since 1903 - winning his second race of this 2015 season.
Castroneves finished second, advancing through the race in an inredibly impressive performance after starting from dead last.
Graham Rahal was unable to go back-to-back, but settled for yet another podium finish, crossing the line as the top Honda-powered Indy car and continuing his successful season.
Follow @VAVELIndyCar on Twitter and stay tuned for more to come regarding this evening's ABC Supply Wisconsin 250 from the famed Milwaukee Mile.
Aaron Durant is the editor of the VAVEL USA Racing section. Follow him on Twitter at @DoubleA291.