On a cold, dark night in the North Atlantic Ocean on April 15, 1912, the “unsinkable” RMS Titanic did the unimaginable: It sank.

While many of us have heard the story (and seen the 1997 movie, of course) many times over the years, what you may not know is how the brave actions of the engineers on board the ship that night may have saved many lives.

A new documentary, Titanic: The Digital Resurrection, studies the first full-sized 3D scan of the ship’s wreckage. It also pulls the curtain back on how workers on board the sinking vessel sacrificed themselves to allow as many passengers as possible to get to safety on the lifeboats.

According to the BBC, the Titanic’s “digital twin” has helped analysts and historians gain further insight into the ship’s tragic destruction, as well as the lesser-talked-about heroism of the night.

READ MORE: Did Any Dogs Survive the Titanic Disaster?

An extraordinary discovery based on the 3D scan backs up eyewitness accounts that engineers aboard the Titanic tirelessly shoveled coal into the ship’s furnaces to keep the electricity on for as long as possible, as passengers fled into lifeboats and into the freezing, pitch-black water of the North Atlantic.

The 3D scan has revealed that some of the boilers that kept the ship’s lights on were concave when the ship sank, suggesting that they were in active operation when the Titanic plunged into the ocean.

“They kept the lights and the power working to the end, to give the crew time to launch the lifeboats safely with some light instead of in absolute darkness,” Parks Stephenson, a Titanic analyst, told the BBC.

An estimated 1,5000 passengers, including all of the heroic engineers and workers on board, died during the Titanic disaster 112 years ago.