Brutus No. 1 was an Anti-Federalist piece of writing that opposed the arguments outlined in Federalist Paper 10 and Federalist Paper 51. Brutus was the pen-name of an Anti-Federalist.
The writing proposed that a small, decentralized republic would be the best choice for the United States because Anti-Federalists were concerned that a government with multiple factions would encroach upon personal freedoms and not be able to adequately represent the people of the United States. They also argued that the Constitution gave too much power to the federal government, which was a bad thing.