Which law provoked a strong reaction from northerners because they worried it would force them to participate in the system of slavery?

The law is Fugitive Slave Act of 1850

Explanation:

The Fugitive Slave Act of 1850 was a law passed by Congress in 1850. It compelled citizens of free Northern states (where slavery had been already abolished) to capture and return any slave that escaped from southern states. 

Northerners feared that the act which mandated them to return escaped slaves back to their southern slave masters would force them (Northerners) to participate in the system of slavery. 

As a result, the law was met with strong reactions from Northerners who strongly resisted it. Some states like Wisconsin and Vermont even passed measures that nullified the law while anti-slavery activists redoubled their efforts in assisting runaway slaves. 

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."

"the sepoy rebellion was the result of many, many influences and stressors on the cultures of india living under british rule. in britain, it's called the sepoy mutiny on the indian mutiny, but in india, it's called the first war of independence.

the main reason is concerned to the british paramountcy , the belief in british   dominance in india political, economic and cultural life had been introduced in india about 1820."

"they were forced to grow crops that benefited the colonizing nations instead of feeding their own people."

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