As part of the Compromise of 1850, which law regarding the return of escaped slaves enraged northerners?

Fugitive slave act.

Explanation:

The Fugitive Slave Act of 1850 infuriated Northern Abolitionists.

In the Compromise of 1850, Henry Clay passed a series of legislation designed to appease (or in the very least, temporarily prevent the inevitable breakup of the Union) both the North and South over slavery. One law that was passed in the Compromise was known as the Fugitive Slave Act. Essentially, this Act allowed Southern slave owners to capture runaway slaves in the North and bring them back. Northern Abolitionists were horrified by slave owners and federal officials coming into the North and taking escaped slaves back to the South.

the answer is

an era of negotiation.

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