Expression: "Only then was I able to understand the situation"

[Tom]

Hi

Could you please tell me if both of my sentences are correct?

1- Only then was I able to understand the situation.
2- Only then I was able to understand the situation.

Tom

[Conchita]

Only the first one sounds correct to me, Tom.

[Pamela]

Hi Tom,

Here is the thread of yours:

Expression requiring inversion: 'By no means, for example!'
http://www.english-test.net/forum/ftopic13996.html

[Yankee]

Hi Tom

Your second sentence would only be OK if your intended meaning for "only" was "but". I assume that was not what you intended, however.

Beginning a sentence with "only then" generally requires inversion of the subject and verb.

Amy