Sorting UNION query by date

Dear Experts

I have the following UNION query... I'd like to sort the entire result set by date but can't figure out how to do this. My first table has CallBankResponse.Date as date, the second has Photos.Date.

Could anybody advise?

Thanks

NIck

SELECT DISTINCT
                        CASE WHEN PhotoZipQueue.PhotoID IS NULL THEN 0 ELSE 1 END AS InBasket, 'CallPictures,' + CONVERT(VARCHAR(100), CallPictures.Picture_ID)
                         AS Passing, OutletList.Outlet_Name + ', ' + OutletList.Outlet_Location AS Caption, CallBankResponse.Date, CallPictures.Picture_ID AS ID,
                         'CallPictures' AS TableName, 'image/jpg' AS ImageType
FROM            CallBank INNER JOIN
                         CallBankResponse ON CallBank.Call_ID = CallBankResponse.Call_ID INNER JOIN
                         ActivityOutlets ON CallBank.ActivityOutlet_ID = ActivityOutlets.ActivityOutlet_ID INNER JOIN
                         OutletList ON ActivityOutlets.Outlet_ID = OutletList.Outlet_ID RIGHT OUTER JOIN
                         CallPictures LEFT OUTER JOIN
                         PhotoZipQueue ON CallPictures.Picture_ID = PhotoZipQueue.PhotoID ON CallBankResponse.Call_ID = CallPictures.Call_ID
WHERE        (CallBank.Username = @Username)
UNION
SELECT DISTINCT
                         CASE WHEN PhotoZipQueue_1.PhotoID IS NULL THEN 0 ELSE 1 END AS InBasket, 'Photos,' + CONVERT(VARCHAR(100), Photos.Photo_ID) AS Passing,
                         Photos.Caption, Photos.Date, Photos.Photo_ID AS ID, 'Photos' AS TableName, Photos.MimeType AS ImageType
FROM            Photos LEFT OUTER JOIN
                         PhotoZipQueue AS PhotoZipQueue_1 ON PhotoZipQueue_1.PhotoID = Photos.Photo_ID
WHERE        (Photos.Username = @Username)
ORDER BY CallBankResponse.Date DESCStart Free Trial