The Philadelphia Project, also known as the Philadelphia Experiment or Project Rainbow, was an experiment that took place on the USS Eldridge in Philadelphia on 28 October 1943. It was conducted by members of the American Brotherhood of Assassins and the German Rite of the Templar Order in an attempt to change the past and alter the present.
While the Templar Order attempted to manipulate world leaders such as Franklin D. Roosevelt, Joseph Stalin and Adolf Hitler to instigate World War II, it eventually became too difficult for the Templars to steer them toward the Order's interests. With their influence over the Third Reich dwindling, they sought to eliminate Hitler instead.
Colonel Boris Pash of the United States Army, a high-ranking Assassin, cut a deal with the Templars after hearing Templar physicist John von Neumann's theories on Die Glocke. An early version of the Animus, von Neumann believed it could allow them to alter the course of history and kill Hitler before his rise to power.
To utilize this plan, Pash recruited Eddie Gorm into the Brotherhood and tasked him with killing Templar Obbergruppenführer Gero Kramer, who intended to use Die Glocke to rise through the Templar ranks. After Gorm's initial attempt in February 1943 failed, he and Julia Dusk succeeded in July 1943, and Die Glocke and the Nazis' Apple of Eden fell into Pash's hands. However, Gorm and Dusk turned on Pash after they were informed of Pash's deal with the Templars by Nikola Tesla, whom they also rescued from Kramer's captivity.
On 28 October 1943, Pash and von Neumann brought Die Glocke and the Apple of Eden aboard the USS Eldridge in the Philadelphia Naval Shipyard in effort to change history by preemptively killing Hitler. However, Gorm infiltrated the ship and killed Tesla, hoping this would stop Pash's project, before subsequently taking his own life.
According to the files of Abstergo Industries CEO Alan Rikkin, the project was ultimately a failure. In an email in 2012, he detailed how the ship instead temporarily manifested in a future state for approximately 18 minutes, and how the Piece of Eden was severely damaged in the process.
Many years later, Abstergo used their Animus Project Subject 12 to collect data on not only this experiment's results, but also on the mechanics behind the artifact and how to repair it. They achieved these goals and managed to reconstruct the Piece of Eden. Nevertheless, Abstergo's administration maintained that the risks of tampering with time—particularly paradoxes—were too unpredictable and dangerous, and subsequently initiated a policy that any objects discovered to be capable of manipulating time were to be securely contained.