Feudalism declined during the crusades because

they undermined feudalism, they lost a lot of money in the wars

Explanation:

The fall of the Roman Empire begin in the medieval age. The medieval age brought the plagues, famines, diseases and in the middle of it all is feudalism. Feudalism or the feudal system was a dominant social system used in western mainly from the 5th to 11th century. In feudal system land are rewarded to lower classes for services, military services and loyalty.

after the civil war, and with the termination of slavery, the south was faced with a big problem; what was supposed to happen and how they were supposed to deal with the freedom and the rights that black people and freed slaves had gained as a result of the north defeating the south and forcing the end of slavery. first, most, if not all, of the workforce of the south came from slaves and they did not have an option to replace the loss of said workforce. second, particularly in the south, people were convinced that black people were lesser, less intelligent, less capable and less smart than whites. this posed a huge problem for them. also, southerners were faced with another issue; freed slaves now had a say in how their lives would be lived and the right to politically choose the way they would be governed. people in the south did not want to accept this, none of this and this opposition and the conflicts that arose from it, not to mention the afereffects of the war, forced the congress of the time to enact and enforce the reconstruction plans that had been proposed by president andrew johnson.

france,russia and prussia had absolute monarchy and it meant:

when louis xiv inherited the throne, he was able to serve as his chief minister.louis xiv ruled as an absolute monarch.