Safety Daiquan Thomasson and Navy teammates at the end of their series-record 14-game win streak vs. Army. (Toni L. Sandys/The Washington Post)

For the first time in 15 years, Navy was first to sing its alma mater after its game against Army. That gloomy distinction falls to the loser of one of college football’s most storied rivalries, one the Midshipmen had owned since installing the triple-option offense.

But that typically efficient rushing attack hardly got on track Saturday afternoon at M&T Bank Stadium, with Navy pinning its fortunes upon a quarterback making the first start of his career. Zach Abey found himself in that uncomfortable circumstance because of injuries to both players who had started the season ahead of him, and the sophomore initially played as if overwhelmed.

By the time the final whistle sounded in a turnover-filled 21-17 loss, Abey had thrown two interceptions, both in the first half, and Navy’s 14-game winning streak over Army, a series record, had ended. The Midshipmen committed three turnovers in all, after just nine through their first 11 games.

“I take a lot of responsibility for the game,” Abey said. “Obviously in the first half I made some bad decisions. I feel horrible for the seniors because I told them before the game that I would give it my all for them.”

“It feels good to be part of the team that kind of put that to an end,” Army Coach Jeff Monken, center, said of the streak. (Toni L. Sandys/The Washington Post)

Abey settled in somewhat in the second half, finishing with 73 yards and two touchdowns on 19 carries and completing 6 of 10 passes for 89 yards. He didn’t receive much help from his teammates, as the Midshipmen amassed just 201 yards of total offense. Navy (9-4) even tried an offensive tweak, using the read option at times, but it mattered little.

In front of an announced sellout crowd of 71,600, Army scored the decisive points on quarterback Ahmad Bradshaw’s nine-yard run with six minutes left in the game, capping a 12-play drive that began at the Black Knights’ 20-yard line. The series included officials overturning a first-down call on third and seven, leaving Army with a fourth and one from the Midshipmen 18.

But sophomore fullback Andy Davidson’s seven-yard run emphatically restored the lost first down, and Bradshaw scored two plays later.

Army (7-5) amassed 351 yards of total offense, including 316 rushing, and finished with a 23-8 advantage in first downs. It also owned a considerable margin in time of possession, 40:32 to 19:28.

Navy went three plays and punted on its final drive, and the Black Knights ran out the remaining 4:07, triggering a celebration in which the entire corps of cadets spilled onto the field.

“We heard for a long time here at West Point about the streak and all that,” said Army Coach Jeff Monken, who once coached on the other sideline as a Navy assistant. “It feels good to be part of the team that kind of put that to an end.”

Navy, meanwhile, dropped consecutive games for the first time since 2014. The Midshipmen lost to Temple, 34-10, last week in the American Athletic Conference championship game at Navy-Marine Corps Memorial Stadium.

In that game, quarterback Will Worth broke a bone in his right foot early in the second quarter, forcing him to the sideline for the rest of the season. The senior had rushed for 25 touchdowns to lead major college football after taking over for original starter Tago Smith, who tore the anterior cruciate ligament in his right knee in the opener.

The Midshipmen were able to make the proceedings competitive following intermission despite a rash of injuries on top of Worth’s absence. Also out were starting slotback and senior co-captain Toneo Gulley, who hurt his left foot against the Owls. Slotback Darryl Bonner was held out as well because of concussion protocol.

The defense already was without three starting linebackers, most notably senior co-captain Daniel Gonzales (Lisfranc injury), and starting cornerback Elijah Merchant (concussion protocol).

“We knew coming into the conference if we played in the championship game, we would only have a week to prepare” for Army, said Navy Coach Ken Niumatalolo, who had won his first eight in a row in the series. “You don’t expect that many guys hurt. We’re not going to use that as an excuse. They outplayed us.”

The Midshipmen had overcome a two-touchdown deficit to take their first lead, 17-14, on Abey’s 41-yard run with 12:42 to go in the fourth quarter. Abey broke several tackles to get beyond the line of scrimmage and finally another that allowed him to dive across the goal line.

Abey had delivered the Midshipmen their first points on a one-yard run with 11:23 left in the third quarter, trimming the margin to 14-7 after taking advantage of a fumble recovery at the Army 29. Navy was able to keep the possession going when, on third and five, Abey completed a short throw to Shawn White that the fullback turned into a 16-yard gain.

The Midshipmen got within 14-10 on Bennett Moehring’s 28-yard field goal with 3:59 to go in the third quarter. The series included a fumble recovered by Army that wound up being overturned upon video review, giving the Midshipmen possession at the Black Knights’ 11.

Army had a 14-0 lead at halftime, courtesy of Davidson’s one-yard run with 7:12 to go in the second quarter. It was Navy’s largest halftime deficit to the Black Knights since 1947.

“This game doesn’t change the way I feel about our team or our program,” Niumatalolo said. “We’ll just keep pressing forward.”