This all is so reminiscent to me of the disastrous Socialist Internationale of Milan 1910. The Socialist Party was too middle of the road for many of the younger more radical members—it was felt that they were too cozy with business, etc, and they were of course, correct. A coalition of the younger folks essentially challenged them from the far left and broke the grip that the more 'moderate' socialists had on the electoral politics of the time. There is much more to the story, but three things tell a tale:

One; the leader of the breakaway coalition was Benito Mussolini.

Two; within no time at all Mussolini, a newspaper editor by this time, had been wholly co-opted by the military industrialists, and began doing their bidding with his newspaper, and began lobbying for war.

and Three; four years after the disastrous Internationale Italy was neck deep in World War I. Mussolini emerged from that war the leader of a new party, the Fascist Party, and Italy has never quite recovered from that.