In what context (historical developments) did nationalism take hold in Europe? In the Americas?

Look at the painting the lictors bring to brutus the bodies of his sons by jacques-louis david (1789). the most likely message this painting sends to french citizens is that one must be prepared to sacrifice their own children to preserve france. loyalty to one’s country stops short of sacrificing one’s own children. brutality is an integral part of revolution and the reign of terror. no one is immune to death, not even the leaders of the revolution.