には驚いた

was surprised by

→ に
phrase Uncommon #10,580
was surprised by Used to emphasize what caused the surprise. It can be followed by a noun or a clause, meaning “I was surprised by...” or “I was surprised that...”
JA: 彼がそんなことを言ったのには驚いた。
EN: I was surprised that he said such a thing.

シャベールには驚いた

I was surprised by Shabert.

— コーラス (2004)

彼の忍耐強さには驚いた

I was amazed by his patience.

その発見には驚いた

I was surprised by that discovery.

彼の無知には驚いた

I was surprised by his ignorance.

あなたの手紙には驚いた

Your letter surprised me.

この地図には驚いた

I was amazed by this map.

— グエムル -漢江の怪物- (2006)

お前のには驚いた

I was surprised by what you said.