sono koudou ni wa yuuki ga hitsuyou datta.

That action required courage.

Breakdown of sono koudou ni wa yuuki ga hitsuyou datta.

• は: topic particle
• が: subject particle
• その: that
• だ: to be

Questions & Answers about sono koudou ni wa yuuki ga hitsuyou datta.

What is the basic grammar pattern in this sentence?

The core pattern is:

A には B が 必要だ

This means B is necessary for A.

So in your sentence:

• その行動には = for that action / as for that action
• 勇気が = courage
• 必要だった = was necessary

So the sentence follows the common pattern:

For that action, courage was necessary.

Japanese often builds this kind of sentence around 必要だ, rather than around a verb like need the way English does.

Why are both に and は used after 行動?

This is a very common learner question.

• に marks the thing that something is necessary for
• は marks that part as the topic

So:

• その行動に = for that action
• その行動には = as for that action / for that action in particular

The は often adds a slight sense of focus or contrast. It can sound like:

• that action, at least, required courage
• when it came to that action, courage was necessary

Without は, the sentence would still be grammatical:

• その行動に勇気が必要だった。

That version is a bit more neutral.
With には, the sentence gives a little more emphasis to that action.