He formed a close association with Jacob Leisler, a rich German-born businessman of rabidly anti-Catholic, staunchly Calvinist views and the leader of a populist political faction known as Leislerians.
[4] Leisler and Milborne instituted a highly autocratic regime under which property was confiscated, mail was opened, homes searched and people were jailed without warrant or trial, and anyone who criticized them was accused of being secretly Catholic or "popishly affected."
It was a strange regime in that its proclaimed purposes were (a) to prevent a Catholic takeover, yet there was no real threat of this given how few Catholics were in New York at the time, and (b) to hold power for the new Protestant king and queen of England, William of Orange and his wife Mary, pending their consolidation of power and sending of instructions and representatives to the colony, yet when the new king and queen sent troops and a new governor, Leisler and Milborne were initially resistant to accepting them.
When a new governor Henry Sloughter arrived with the resources to put down the rebellion, Leisler and Milborne surrendered to him, but not before shots were fired and lives were lost in a standoff at the fort.
[9] In 1698, largely thanks to the sympathetic efforts of the then governor, Earl of Bellomont, the bodies of the two men were disinterred and reburied at the Dutch church and their estates were later restored to their heirs.