I am well into my next book on Rum. This is a very interesting complete history of Rum. I am in to about 1/3 the way and already, Rum: The Epic Story of the Drink that Conquered the World [Charles A Coulombe - Citadel Press], has me mesmerized. 
While Sugar told us of the history of sugar and how that gave birth top the Age of Sugar as well as Rum itself. It also chronicles the growth and proliferation of slavery not just in the USA but across the world, the sugar industry being the biggest user of free, forced labor. Rum: The Epic Story of the Drink that Conquered the World zero's in on Rum, it's birth growth and many of the reasons we think of it as a spirit, even today. Even its responsibility towards making certain words and phrases we use almost daily, like limey, Scuttlebutt and grog.

When British Sailors drank their daily ration of rum, it was "neat" in the beginning. Since rum was not cut to proof it - it varied in the 140-160 proof region. Needless to say the 1/2 pint drunk at once was a shock to the system, and most likely lead to many on ship accidents. They learned to mix it with water and even add lime and/or lemon juice as well as sugar. So now you had the start of a "Punch" that was 4 oz Rum with a quart of water or water-mix of lemon and lime juice as well as a measure of sugar. Rum Punches became a popular drink (Still is) the first and one most "Official" is the:
Mix that and serve and you approximate the same drink enjoyed by many British sailors -- The daily ration would be about 40 oz of that mixture... just a quart and 8 ounces. 

I will keep you all apprised of it all as I go and do a complete report when finished.