Carlos Ghosn, who was arrested this week for allegedly falsifying details of his compensation, was reportedly planning to merge Nissan and Renault before his downfall.

Ghosn was the chairman of both companies, as well as Mitsubishi, and was also the CEO of Renault—the French carmaker on Tuesday replaced him on an interim basis with chief operating officer Thierry Bolloré. Indeed, he is for now still the chair of Nissan and Mitsubishi, though he will likely be ousted very soon.

In effect, Ghosn was the glue holding together an alliance of the three auto firms. Mitsubishi CEO Osamu Masuko said Tuesday that he did not think “there is anyone else on Earth like Ghosn who could run Renault, Nissan and Mitsubishi.”

According to a new report from the Financial Times, Nissan’s board opposed Ghosn’s plan to merge Nissan and Renault—a plan that was set to materialize within months, according to the paper’s sources.

The merger would have rendered the Renault-Nissan alliance “irreversible.” The two companies already hold shares in one another—Renault owns 43% of Nissan and Nissan owns 15% of Renault, so the French firm has the upper hand.

According to one FT source, Nissan’s board “always said they would fight very hard against any reorganization that entrenched that second-tier status.” There was apparently great tension between Ghosn and Nissan CEO Hiroto Saikawa.

Ghosn’s arrest followed a months-long internal investigation at Nissan, of which Ghosn was apparently unaware until Monday.