There are wars where the two parties fight in the hope of seizing territory, righting a wrong or making a point, before settling the conflict with a deal each hopes will be advantageous to their interests.

And then there is total war, when each side knows that the fight only ends in the total destruction of one side, or perhaps even both.

Jeremy Corbyn has today confirmed that the struggle underway in the Labour Party is now the political equivalent of total war.

He did it with these words, at the launch of his campaign to keep his job, when he was asked whether Labour MPs should face mandatory re-selection to stand again as Labour candidates at the next election:

"There would be a full selection process in every constituency but the sitting MP... would have an opportunity to put their name forward.

"So there will be a full and open selection process for every constituency Labour Party through the whole of the UK."

This what many Labour MPs have feared and expected since Mr Corbyn became leader, but it is still a big deal. Very big.