When the System Lord Svarog attacked Latona in 2002, he believed the Caretaker would use the Sentinel to drive them away. Unfortunately, the Caretaker had been killed by Colonel Sean Grieves years earlier, and was unavailable to activate the device. Fortunately, the Sentinel was activated when Grieves took the Caretaker's place, and the attacking Jaffa and Ha'tak were made to disappear, along with Grieves himself. (SG1: "The Sentinel")