What does the word waning mean? What happened to the north’s resolve to continue with reconstruction?

I inferred your second question is referring to Political reconstruction plans in the United States.

1. Implies an ongoing reduction in previous form or state.

2. It failed initially.

Explanation:

1. This verb is often used to describe an ongoing process leading to decrease or reduction in the state of something or someone.

For example, "The immigration policy is waning in its popularity".

2. It is noteworthy historically that during the days of Abraham Lincoln the reconstruction plans of the North were not immediately successful, because Africans Americans were not in support of the certain policies in the plan.