Learn French: Ne le force pas à attaquer. - Do not force him to attack.

In French, many verbs require a specific preposition before a following infinitive. The verb forcer (to force) takes the preposition à when it is followed by an action. The complete structure you are learning here is forcer quelqu'un à faire quelque chose (to force someone to do something).

Why is the pronoun le placed before the verb instead of after it?

In affirmative commands, object pronouns attach to the end of the verb with a hyphen, like Force-le (Force him). However, in negative commands like this one, the pronoun moves back to its standard position right before the verb. That is why it becomes Ne le force pas.

Since this is a command for "you" (tu), shouldn't force end with an "s"?

For regular French verbs ending in -er (like forcer), you must drop the final "s" in the tu form of the imperative (the command form). So while a normal statement would be Tu le forces, the command drops the "s" to become simply force.

Could I use lui instead of le here to mean "him"?