When precisely was the ‘event within history’ to which you refer, Andrew - the parousia when ‘Caesar was displaced’, and how did anybody know that this event had taken place? We could with greater validity be talking about the death of Jesus on the cross - Colossians 2:15, except that the language of 1 Thessalonians 4:13-18 doesn’t fit, which moves it forward to an as yet unaccomplished event. The more you seek to prove your case, the less convinced I am that there is any historical evidence for it on the terms with which you describe it. Without historical evidence, it lacks credibility. A credible faith needs more credible evidence.