Nail your colours to the mast
Definition 1 of 1
Pro Tip 1/3Metaphoric Origin
Originally, 'nailing your colours to the mast' referred to ships' flags, symbolizing a refusal to surrender. 
Even when the outlook was bleak, the CEO nailed his colours to the mast, keeping faith in his company's mission.
Pro Tip 2/3Bravery Implied
Using this phrase often implies bravery or commitment since it suggests taking a risk for one's beliefs. 
She nailed her colours to the mast by defending her project in front of the skeptical investors.
Pro Tip 3/3Irreversibility
The phrase can imply a point of no return, indicating a definitive public commitment. 
After he nailed his colours to the mast on live TV, there was no going back on his statement.