take up the cudgels for somebody/something
take up the cudgels (for/on behalf of someone or something)
To defend, show strong support for, or argue on behalf of someone or something. People from across the country are taking up cudgels on behalf of the young man being held by police. He's got plenty of money to hire a proper legal team. I don't think he needs the likes of us taking up the cudgels.
take up the ˈcudgels for somebody/something,
take up the cudgels on behalf of somebody/something(old-fashioned, written) start to defend or support somebody/something: The local newspapers have taken up the cudgels on behalf of the woman who was unfairly dismissed from her job because she was pregnant.
A cudgel is a short thick stick that is used as a weapon.