What is それ referring to in this narration?


I think that I am probably over thinking this which has lead to me become
confused as to what それ is referring to below.

To provide some additional context, the main character had just asked his
friends 「みんな、大人と戦う覚悟はできてるか？」and the below extract begins after their answers.

> そうか……。そうだった。
>
> こんなこと、聞くまでもなかったんだ。改めてみんなの気持ちを確認する必要なんてなかったんだ。
>
> 覚悟なんて、とっくの昔に固まっていたんだから。
>
> 「みんなで、この世界を守り抜こう。たとえ、誰がここに攻めてきても、追い返してやるんだ！」
>
> みんなが笑顔で頷いてくれる。
>
> 最初から、 **それ** だけで十分だった。

I was originally thinking that それ was referring to the utterance
「みんなで、この世界を守り抜こう。たとえ、誰がここに攻めてきても、追い返してやるんだ！」, i.e. this was all he had to say
in the first place (instead of asking the proceeding question to confirm their
resolve). However, then I thought that if he was actually saying this then his
utterance would have been worded differently which now leaves me a bit
confused as to whether he is saying what I originally thought, or if he is
referring to [みんなが笑顔で頷いてくれる].

I would appreciate if the answerer could clarify which is correct, (and
potentially how the sentence would have been worded differently if they
intended the other meaning).




IMHO this それ refers to what he said: "みんなで (snip) 追い返してやるんだ！", as you
initially thought. The shortened context is something like this:

> I did not have to ask "Do you want to do this?", but just **saying "Let's do
> it"** was enough.

I'm not sure why you thought "if he was actually saying this then his
utterance would have been worded differently". From what I can see, this line
is what he actually said to みんな. Otherwise, they could not have nodded.

