29th Division Battle Orders

[sherren]

I am looking for advice on where to find official records of battle orders and specifically documents pertaining to when a regiment or brigade (or other military unit) is attached?
My specific interest is with respect to the 29th Division and when the 1st Newfoundland Regiment was so ordered or attached. They were part of the 88th Brigade during their landing at Gallipoli in September, 2015, however I have yet to find anything like official battle orders that confirm this.
Perhaps I need to be looking for orders with respect to their assignment with the 88th brigade first? 
Any assistance in my search would be greatly appreciated. 

[michaeldr]

There is a transcript of the regiment's War Dairy here https://www.therooms.ca/sites/default/files/war_diary_-_complete_-_sept_1915_-_feb_1919.pdf 
and on page 5 you will see that while at Polygon Camp, Cairo, on 4th September 1915, they were

“Attached to the 1/1st London Infantry Brigade (Authority: Letter C. R. 9774 dated 4/9/15)”

It would be interesting to see that letter which is cited as “Authority” as there's a good chance that there is a transcription error - I think that it probably should read 2/1st London Infantry Brigade 
See https://en.wikipedia.org/wiki/2/1st_London_Brigade where it is noted that this brigade went to Suvla, but was used as reinforcements for the 29th Division's 88th Brigade

[sherren]

Thanks very much michaeldr. While I had looked over the regiment's War Diary I had missed the statement regarding the "Authority". I had thought that the regiment had received battle orders prior to leaving Britain. Unfortunately the War Diary only begins in September 1915. You are correct that the 'Letter C. R. 9774' should explain more and I will look for that. 

Your quick response is appreciated.