From iCloud iCal to Google Calendar

From iCloud iCal to Google Calendar

I would like to export my iCloud iCal on my computer to import it into my
Google Calendar. I don't find a working solution. Here is the method I
just tried:
Log in on my iCloud account.
In iCal, I share publicly the considered calendar.
I copy the address in a browser but I replace the webcal:// by http://
It downloads a .ics file
When I try to import that file into my Google calendar, it fails...
Where am I wrong ?
Thanks for your help.