To start a battle in English, you can say "let's start the fight," "let's begin the battle," or "let's engage."

The phrase "let's start the fight" is a colloquial way of saying that two parties are ready to engage in a physical confrontation. It is often used in informal situations, such as when two friends are play-fighting or when two sports teams are about to compete against each other.

The phrase "let's begin the battle" is more formal and is often used in a more serious context, such as when two armies are about to engage in a war.

The phrase "let's engage" is a military term that means to start fighting. It is often used in a military context, such as when two opposing armies are about to clash.

Here are some examples of these phrases in English, along with their Chinese translations:

Let's start the fight! (让我们开始战斗吧!)

Let's begin the battle. (让我们开始战斗.)

Let's engage. (让我们开始战斗.)