Question: The Freemen of the South, were belligerents in an 1839 rebellion in south Buenos Aires province, Argentina against Federalist Governor Juan Manuel de Rosas, a mixture of disgruntled ranchers and Unitarian revolutionaries, the Freemen briefly took control of Dolores, Chascomús and which main city of the homonymous partido (department), located in Argentina, in the southeast of Buenos Aires Province, just north-northwest of the Tandilia hills?
Sentence (from "Tandil"): The city was founded in 1823 and its name originates from the "Piedra Movediza" ("Moving Stone") which later fell.
Relevant evidence: No