Simple Syntax Error - CASE WHEN DISTINCT(Column) Trying to do a case on a distinct value and it isn't going well:

SELECT
CASE WHEN DISTINCT(Response_Master_Incident.Battalion) = '' THEN 'Unknown'
    ELSE DISTINCT(Response_Master_Incident.Battalion) END AS 'Zone'
...


and I get the error "Incorrect syntax near the keyword 'DISTINCT'."
Answer looks like this.  Thanks Randolph!

SELECT DISTINCT
    CASE WHEN Response_Master_Incident.Battalion = '' THEN 'Unknown'
    ELSE Response_Master_Incident.Battalion END AS 'Zone'