Thud is one of five "huge" and "formidable" cities that form an arc east of the Plain of Fear in the northern continent, the others being Rust, Frost, Ade, and Barns.
Thud, part of the Lady's Empire, was lost to the Rebel, but would be reclaimed by the Taken known as Nightcrawler. At least 12 years later, in The White Rose, the city would again take up the Rebel cause against the Lady, now as part of the New White Rose Rebellion.
Before Croaker's Annals
The city of Thud was conquered during the consolidation wars of the Lady's Empire, presumably by one or more of the Ten Who Were Taken and their armies. It became part of the border arc of the empire's eastern frontier, in a line along with at least four other massive nearby cities: Frost, Ade, Barns, and Rust.
Then, sometime in the decades afterward, Thud became part of the Rebel movement headed by the Circle of Eighteen. The stubbornness of the best general in the Circle, Whisper, held the eastern front together despite the best efforts of the Taken.
The Black Company
Whisper, formerly the champion of the Rebels, was Taken (enslaved) by the Lady. This precipitated the rapid collapse of the Rebel in the east. Two of the Taken – Nightcrawler and the Faceless Man – led separate armies across the Plain of Fear to retake Thud and Barns respectively. Shortly before this, Whisper reconquered Rust, then Frost, for the empire, and the Circle general Parcel reportedly committed suicide at Ade to avoid capture by Bonegnasher, an 8-foot tall cannibal among the Taken.
Soulcatcher proudly informed the Annalist Croaker of all these developments during the Black Company's own struggles with the Rebel at the Stair of Tear.
After Thud was reconquered by Nightcrawler, it again became part of the border arc of the Imperial eastern frontier. But in just six years, as Croaker would record with awe in Shadows Linger, the empire had stretched far beyond Thud and that arc of other cities, into the formerly independent kingdom of Tally.
The White Rose
Thud apparently became a significant supporter of the New White Rose Rebellion by the time of The White Rose. In response, one of the new Taken called Blister was given control of the imperial army there, and raised his or her stela within the city. This was part of the Lady's encirclement of the Plain to entrap her enemies Darling and the Black Company – the nucleus of the New White Rose Rebellion – who had been directing Rebel activity from a cavern called the Hole there for two years.