The phrase "a decisive victory on" is correct and usable in written English.
It can be used when discussing the outcome of a competition, battle, or contest where the result is clear and significant.
Example: "The team achieved a decisive victory on the final day of the tournament, securing their place in the championship."
Alternatives: "a clear win in" or "an overwhelming success in".
He predicts a decisive victory on Sept. 14.
Macron won a decisive victory on Sunday night with more than 66% of the vote against the far-right Marine Le Pen's 33.9%.
But his cheeks were puffy, a telltale sign of heavy steroid treatment, as he voted, delivering Democrats a decisive victory on a signature health care issue.
The United States had already clinched its first-round Davis Cup series against Austria, and Roddick had already pleased fans with a decisive victory on Friday.
One of those is Roberval-Lac St. Jean where Denis Lebel, a local mayor, brought the party a decisive victory on Monday.
If every underdog has his day, this was Bill White's as he savored a decisive victory on Saturday in the runoff for mayor of Houston.
Nov. 8, 2016, 9 14 p.m. California voters handed a decisive victory to Gov. Jerry Brown on Tuesday in his effort to reshape the state's criminal justice system, approving a ballot measure to offer a new chance at prison release for thousands of prisoners.
As the first black American president, many saw his presidency as a decisive victory for civil rights and cheered him on when he pushed for serious socioeconomic changes.
The forces of the majority, ably led by Henri Dufour, took Fribourg on November 14 and Zug on November 21; they won a decisive victory at Gislikon on November 23, entered Luzern itself, the nucleus of the Sonderbund, on November 24, and subdued Valais on Nov. 28, 1847.
Unable to win a decisive victory at Borodino on September 7, the only full-scale engagement of the campaign, Napoleon was eventually forced to retreat.
Toward the end of 49 bce, he followed Pompey across the Adriatic and retrieved a reverse at Dyrrachium by winning a decisive victory at Pharsalus on August 9, 48 bce.
