bloody, fierce
intense, pitched
The two armies fought a pitched battle on the plain.

climactic, decisive, final
Iwo Jima was for many the climactic battle of World War II.

epic, famous, great, historic, important, major
land, naval, sea
coming, upcoming (AmE)
The squadron was getting ready for the coming battle.

fight
win
lose
do, enter, give, go into, join, wage
Charles V refused to give battle.
The two armies joined battle.

send sb into
Many young men were sent into battle without proper training.

survive

begin, ensue, take place
rage
continue, unfold
The leaders anxiously watched the battle unfold.

be over, end

at a/the battle
Napoleon was defeated at the Battle of Waterloo.

in (a/the) battle
He died in battle.

fierce
pitched
running
gun
turf (esp. AmE)
A turf battle among competing drug cartels has claimed several lives.

fight

erupt

battle against
Police fought a pitched battle against demonstrators.

battle between
a gun battle between police and drug smugglers

battle with
Scores of people have been hurt in running battles with police.

bitter, fierce, heated, intense, tough
a heated battle between the oil industry and environmentalists

real
There's now a real battle at the top of the First Division.

constant, continuing, epic, long, long-running, ongoing, prolonged, running
The college president fought a running battle with the editors of the student newspaper.

coming, upcoming (AmE)
The upcoming political battle could be for the allegiance of the young.

losing, uphill
We seem to be fighting a losing battle.

successful
court, custody, legal

do, engage in, fight
Are you prepared to do battle with your insurance company over the claim?

be engaged in
face
win
lose
end
She saw a way to end the prolonged legal battle.

rage
A policy battle is raging in Washington.

begin, ensue
A ten-month legal battle ensued.

be brewing, be looming, loom
A battle is brewing between ecologists and big business.

be over, end

battle against
his long battle against cancer

battle between
a fierce battle between developers and the local community

battle for
the battle for human rights

battle over
The government now faces a new battle over tax increases.

battle with
They are engaged in a long-running legal battle with their competitors.

a battle of ideas, a battle of words
a battle of wills, a battle of wits
a battle royal (= a major battle in which all available forces take part)
fight your own battles
My parents believed in leaving me to fight my own battles.

pick your battles (= decide which things are worth fighting or disagreeing about)
As a parent, you have to pick your battles.