For verily, when we were with you, we told you before that we should suffer tribulation; even as it came to pass, and ye know.
That we should suffer - `that we are (sure) to suffer' by the appointment of God (1 Thessalonians 3:3).
Even as - `even (exactly) as it both came to pass, and ye know by experience:' ye know both that it came to pass, and that we foretold it (cf. John 13:19). Prophecy's correspondence to the event confirms faith. 'Forewarned, forearmed' (Edmunds). The repetition of "ye know" is an argument that, being forewarned of coming affliction, they should be less readily "moved" by it.