IF isBlank on multiple columns return first nonblank date.

Hello all-

I am trying to create a new column called in this example "Issued Date"  What I need it to do is look back at Date4 and if it has a date put that date in.  If blank look at date3.  If it has a date return that one otherwise going to Date2 and so on.  I can do it between two columns but as soon as I add a third and forth I get two many arguments errors.  Anyone have a work around?