When we talk about achieving something on a specific occasion in the past, we use was/were able to (= had the ability to) and managed to (= succeeded in doing something difficult).

Was were be able to?

We use could to talk about an ability somebody had in the past. We use was/were able to to talk about a specific event in the past.

Was were able to is used to express?

I managed to persuade her to volunteer at the show. Now let's talk more about the meanings. “Was (or) were able to” and “managed to” both suggest effort. They mean someone succeeded in doing something that was a challenge or took a special effort.