Captain of the 29th Battalion on Board Ship. Purchased at an antiques flea market.
Because I bought this in Vancouver, I’m assuming this the ship is Canadian. Here’s the Wikipedia entry for the 29th batallion. also known as Tobin’s Tigers.
The inscription on the back is precious. Notice (she?) says old George is as fat as ever. Standards of fatness were different in 1915.
I purchased these with several other paper ephemera that day. I almost felt conned, or suckered in, and they have all sat neglected in an envelope these last two years. Taking this photo out in particular feels like the purchase was well worth the nominal investment.
Status: Decipher last name of fat George and see if I can find any history of him. And if it does say “Dad” beside the word “Capt.” find out who Dad was.
Obsolescence Project 
Yes, you are right it does look more like Dr than Dad. It is fabulous to have the name and date of photographer – a very meticulous woman – (I’m only assuming it’s a woman of course, based upon handwriting and care – gross assumptions)
I wonder if it says “Dr.” & not “Dad”–none of the other letter “A”s are printed, which would lead me to think this is not an “A.” Just speculating. It would likely be possible to figure out who George is, with his name nearly decipherable and all. It’s wonderful & unusual to have the date & name of the photographer noted there, too.