Was entering World War 1 an ethical response on the part of political leaders?

Any nation entering World War One was in the conflict due to treaties, nationalism and greed. All or one of these were applicable. The ethical nation would not sacrifice its people as was done in that war.

Entering World War One was based on various European treaties and alliances. Any such treaty or alliance can be broken if it leads to unethical results according to the party or parties involved. WW 1 could have been avoided if outrageous nationalism and power seeking nations restrained themselves. As an aside, most major multi-nation wars fit into the World War One model.