Sql Query help

Issue:
Trying to bypass programming limitations to solve a customers problem. They are trying to import DOB into our system as mmddyyyy. Our system does not understand this value and its hardcoded to accept mm-dd-yyyy or mm/dd/yyyy. So to bypass I am importing this into the Country field instead of the DOB field

I then run this query
update Patrons set Country = LEFT(country,2)+'/'+substring(country,3,2)+'/'+RIGHT (country,4)

This turns the raw data into the format I need. What I cant seem to figure out myself is the query to say update patrons set country = dob

Heres what I have so far

update Patrons set DateOfBirth = cast(country as daTE) where LEN(Country) =10

Conversion failed when converting date and/or time from character string.

I know I am close but I am missing something. Any ideas?

try converting to yyyy-mm-dd first, instead of mm/dd/yyyy, before doing the CAST