It was a second successive away win for Ivybridge following their 7-0 victory at Ottery St Mary on Saturday and saw them move to fourth place in the East Division table.
Ivybridge leapfrogged over Dartmouth and also climbed above Newton Abbot Spurs, who were held to a 0-0 draw at Elburton on the same evening.
The win at Dartmouth was all the more impressive as Ivybridge were again without injured full-backs Curtis Legrice and Jake Lane, while Sam Ryan and Callum Merrin were also ruled out by injury.
But they were boosted by the return of Owen Raven for his first game in a month while 17-year-old Callum Collings did not put a foot wrong in a man of the match performance at right-back.
After a goalless first half Ivybridge broke the deadlock on the hour when Fletcher Williams scored his 11th goal of the season after being set up by his brother Mitch.
Ivybridge wrapped up their win with goals in the 80th and 85th minutes from Ewing, who has been signed from Devon Football League side Topsham.
Manager Darren Stewart said: “It was a fantastic result for us. I am pleased with the way the players have responded in the last two games following our defeat in the semi-final of the League Cup last week.
“It was important that we did not let the season fade away and we have set ourselves the target of a top four finish.”
Ivybridge will look to continue their good form on Saturday (April 9) when they visit Honiton for their third away game in eight days and hope to strengthen their squad with the returns from injury of Legrice and Merrin.
Despite being third from the bottom of the table, Honiton will be defending a five-match unbeaten run.
Following their busy time on the road, Ivybridge have two home games at Easter with the return clash against Dartmouth at Erme Valley on Good Friday morning (11am) followed by a visit from Bovey Tracey on Easter Monday (2pm).