Why was 1750-1800 an opportune moment for some to take action for change

The belief that war often drives civil modifications to a society is based upon the evidence that in times of external conflict, a society is forced to abandon long held discriminatory values to:

Nationalism led to major conflicts following world war i, especially when:

The quote below is an excerpt from the charter of the united nations: "the purposes of the united nations are: to maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats to the peace, and for the suppression of acts of aggression or other breaches of the peace, and to bring about by peaceful means, and in conformity with the principles of justice and international law, adjustment or settlement of international disputes or situations which might lead to a breach of the peace . " source:this section implies that the united nations is prepared to do what to keep world peace?