Questions & Answers about Atak był niespodzianką.
Because after być in this kind of sentence, Polish often uses the instrumental case for the noun that describes what something was.
So:
- niespodzianka = nominative, dictionary form
- niespodzianką = instrumental singular
This is very common in Polish:
- On jest nauczycielem. = He is a teacher.
- To była katastrofą. = It was a catastrophe.
- Atak był niespodzianką. = The attack was a surprise.
For many feminine nouns ending in -a, the instrumental singular ends in -ą.