The second season of NBC's hit family drama series "This is Us" featured a major look back to the past, revealing some significant events that made the Pearsons who they are now. Perhaps the most impactful, yet heartbreaking, throwback of the season is the revelation of Jack Pearson's (Milo Ventimiglia) cause of death.

In season 3, fans are likely to witness another trip down memory lane that is still focused on Jack. This time around, his past in the military will be explored.

The season 2 finale of "This is Us" had some flash-forward scenes that reveal the older versions of Tess and Randall. There was also an interesting glimpse of an alternate future wherein Jack Pearson did not perish from the fire and reached his elder years.

In season 3, viewers can expect another time travel to the past, which will recount Jack's experiences in the Vietnam War. In an interview with People magazine, Ventimiglia revealed that "This is Us" will once again delve into Jack's past.

"We're definitely going to see Jack in the Vietnam era," the actor confirmed.

He mentioned a particular scene at the end of the Super Bowl 2018 episode that showed how his character passed away following the fire at the Pearson residence. There was a hint of Jack in his military uniform, going to a helicopter bound for Vietnam.

In season 3, the fans will see how his life went during the war.

"We're going to explore that side of Jack's 20s and what brought him into the man that we all knew," Ventimiglia added.

This is a proof that Jack Pearson will always be an integral part of "This is Us" even if the character is already deceased in the show's present timeline.

As for the flashback sequences to Jack's military service in the Vietnam War, season 3 is expected to explain how this experience in his younger years made him a strong and loving patriarch until his death.

It is also rumored that the Vietnam War flashback will formally introduce the viewers to Jack's brother, Nicky, whose death might have affected the former's outlook in life.

"This is Us" season 3 is expected to premiere in September 2018.