Cross swords
To engage in a dispute or argument.

At loggerheads
In disagreement or in conflict.

Bite the bullet
To face a difficult situation bravely.

Throw in the towel
To give up or admit defeat.

A house divided
A group or organization that is in conflict with itself.

Burn bridges
To destroy relationships, making it impossible to return to the previous state.

Clash of titans
A conflict between two powerful opponents.

Between a rock and a hard place
To be faced with two difficult choices.

Stir the pot
To create conflict or tension in a situation.

Go to war
To engage in a conflict or struggle.

Kicking the hornet's nest
To provoke a conflict or create problems.

Fight fire with fire
To respond to an attack or conflict with a similar approach.

Pick a fight
To intentionally start a conflict.

A bitter pill to swallow
An unpleasant situation that must be accepted.

Tug of war
A struggle for power or control.

Not seeing eye to eye
To have a disagreement or differing opinions.

Let sleeping dogs lie
To avoid interfering in a situation that could cause conflict.

Adding fuel to the fire
To make a conflict worse.

On the warpath
In a state of anger or readiness to fight.

Head-to-head
Direct confrontation or conflict.