I'm interested in the economic and financial histories of national debt, warfare, kingdom/empire building, alliances, etc. I'm partial to history before WWII.
Is there any title that I should look for?
Double Entry: How the Merchants of Venice Created Modern Finance by Jane Gleeson-White is good history of double entry bookkeeping. It focuses on banking practices in northern Italy in the 14th/15th centuries. Technical, but very readable as I recall (my understanding of finance is terrible).
The Worldly Philosophers: The Lives, Times And Ideas Of The Great Economic Thinkers by Heilbroner is a good read, although I'm not really sure if it's exactly what you're looking for.
Goetzmann and Rouwenhors, "The Origins of Value: The Financial Innovations that Created Modern Capital Markets"
A great resource covering a plethora of different origins and developments in financial/business history. However, the book is prohibitively expensive for all but the specialist. Hopefully you have access to a university library or a big public library and can check out a copy there.
Niall Ferguson's 'The Ascent of Money' is quite a good general introduction, it's very accessible since it was written for a general audience to accompany a documentary TV series.
He writes from an economically conservative perspective, embracing neo-liberal, pro-capitalist ideals, so I wouldn't read it in isolation if you want to get a fully rounded picture because many economic-historians to the left of him disagree with his viewpoints, nevertheless if you want a spring board for the subject it would be a useful place to start. But bear in mind that it does simplify things significantly, it's not meant to be a text book.
I have two suggestions that you may want to look into.
The first is Vol. II of Fernand Braudel's Series "Civilization and Capitalism". It give a good overview of how European financial systems developed in tandem with other elements of economic life - particularly local and international trade.
The second is "Manias, Panics, and Crashes: A History of Financial Crises". An entertaining but very thorough read on why financial crises occur - you end up learning a lot about how the global system has changed over the past several hundred years.