What is the title of the first Assassin's Creed game to feature the Brotherhood management system?

Assassin's Creed: Brotherhood is the first Assassin's Creed game to feature the Brotherhood management system.

Released in 2010, Brotherhood continues Ezio Auditore's story in Renaissance Rome. Ezio can recruit civilians, train them as Assassins, assign them to missions, and call them for assistance during gameplay. This system makes the organization itself a major gameplay feature.

The game also expands the series' modern-day plot and introduced the franchise's first competitive multiplayer mode. Its central conflict involves the Borgia family, especially Cesare Borgia, whose control over Rome threatens the Assassin network.

Assassin's Creed II includes Ezio's initial transformation into an Assassin but does not use Brotherhood's full recruitment-and-management structure. Revelations later develops the system further, but it was not the first title to introduce it.