This is a question to which I don't have an answer - just thought it was interesting. Last December, the president of the Philippines declared a “state of national calamity” following a typhoon. The more familiar phrase is “state of emergency.” Is there a difference?
Apparently, Britain’s war in Malaya in the 1950s was officially an “emergency” because owners of rubber plantations lobbied the government. They were worried that if it were called a “war,” their insurers wouldn't have to pay up for the destruction done to their businesses by guerrillas.