Which piece of legislation was an important step in limiting slavery

Missouri compromise

Explanation:

Contradictions between the slave system in the South and the system of free wage labor prevailing in the North manifested at the end of the second decade of the 19th century. The first open clash between the North and the South, which created the threat of a split in the country, was the conflict of 1818-1820. It arose in connection with the issue of admission of a new state - Missouri - to the union. At that time, the United States included 11 slaveholding and 11 free states. Opponents of slavery in Congress demanded a prohibition on slavery in Missouri, because accepting it into the union as a slaveholding state would create a numerical superiority of slaveholders in the Senate. Slavery first appeared as a national problem, which was discussed by the whole country.  

As part of the Missouri compromise, northerners in Congress tried to limit the spread of slavery. In 1820, Missouri was admitted to the union as a slave state, and the territory of slavery expanded somewhat, but at the same time the newly formed free state of Maine was adopted. It was decided in the future to simultaneously accept two states in the union: one free and one slaveholding. At the same time, an agreement was reached that north of a certain border slavery was prohibited (a parallel 36° 30' north latitude was established by the border).

However, the geographical restriction of slavery established by the Missouri compromise did not eliminate the contradictions, but only postponed the conflict between supporters and opponents of slavery.

i believe we're not a republic so that is a hard question

a, he promoted disarmament