Conversation so far:
how was Billy Hughes as prime minister?
His former colleagues in the Labor Party considered him a traitor, while conservatives were suspicious of what they viewed as his socialist economic policies.
what did Billy Hughes do to be a traitor?
Hughes' opponents accused him of engaging in authoritarianism and populism, as well as inflaming sectarianism; his use of the War Precautions Act 1914 was particularly controversial.
what were some things Billy Hughes did as Prime Minister?
The government replaced the first-past-the-post electoral system applying to both houses of the Federal Parliament under the Commonwealth Electoral Act 1903 with a preferential system
what's some interesting things Billy Hughes did as Nationalist Party Prime Minister?
The Governor-General, Sir Ronald Munro Ferguson, persuaded Hughes and Liberal Party leader Joseph Cook (himself a former Labor man) to turn their wartime coalition into a formal party.

Question: how did he persuade him to do that?
Self-contained rewrite: how did Ferguson persuade Hughes to turn their wartime coalition into a formal party?