Sorry,

I will soon close German forum, as no volunteer anymore to give support...

But i have understood your problem.

Today, iCagenda is using the uniw time, and php function to perform action on dates. But, Uniw timestamp used for dates is only beginning on 1 january 1970, and with an end of life arround 1 january 2038 due to a bug in this date system logic.

I don't have planned today to give this possibility yet, because this will need to have a individual date management for dates before 1st january 1970.
So, maybe i will see on day for this possibility (but with no date formating as iCagenda is using today). Just this feature for date before 1970 won't be developped before one year, as i have other priorities today in the major developpements for iCagenda.

Today, iCagenda is an event mangament, but is not meant to manage historic dates.

My Best Regards,
Lyr!C