Back in 2011 when Jim Harbaugh was coaching the San Francisco 49ers, a handshake between himself and Detroit Lions head coach Jim Schwartz started a scrum.

More than half a decade later, Harbaugh, now coaching at Michigan, is taking responsibility for sparking the drama.

“I went in too hard on that, too aggressive on the handshake,” he said an interview on Barstool Sports’ Pardon My Take podcast. “We’ve talked, and we’re good. We’re back to friends. … There is a protocol in a postgame handshake. I’ve been there as the winner. I’ve been there as loser. You just, ‘Nice game,’ then go celebrate. Premature celebration there, in the wrong.”

For those who might not remember the incident, here’s a trip down memory lane.

To be fair to Harbaugh and Schwartz, both are fiery guys by nature. And this was an intense game, in Harbaugh’s first year as a head coach in the NFL.

Before Colin Kaepernick ever took over the 49ers offense, Alex Smith was still the man behind center. And he orchestrated an impressive fourth-quarter touchdown-scoring drive to take the lead against the then-undefeated Lions.

The 49ers then scored three more points on a field goal following a turnover on downs by Matthew Stafford and Co., then closed the game out with a strong defensive stand.

Then Harbaugh celebrated jubilantly with his players before going in hard with the old handshake/slap on the back. Schwartz went ballistic, and the two teams nearly got into a legendary fight after the final whistle.

Thankfully nothing more ever came of that incident. Though, Harbaugh still can’t stop himself from acting out and/or throwing tantrums like a kid on the sidelines, even when he’s winning.