Does the Italian national debt really go all the way back to Mussolini's excessive prewar spending? The WWI &amp; WWII debt is  quite well defined in the UK for example and quite shocking how many years it took to pay off.

Somebody told me that the Italian debt crisis really goes all the way back to Mussolini's excessive prewar spending and in 2011 Berlusconi defended Italy's debt crisis as he argued it went back to the war and was just the way the country runs.

What is the true reason? Given that a country such as Russia managed last year to pay off all the Soviet debt it seems quite strange that a G7 economy like Italy could have a debt going back to Mussulini's era starting in the twentys. 

Obviously a countries debt is made up of many things such as public spending and in all countries but chronically in some corruption. But there often is an isolated or small number of decisions, policy or event that accountants for the beginning of the problem.

P.S is this question perhaps for the history stackexchange?

Some historic/economic background is summaried here: https://en.wikipedia.org/wiki/Economy_of_Italy_under_fascism
Debt Crises are the inability to pay interest on the debt a country has already taken up to that point. There are many theories, about how such crises can develop, however all have one thing in common. You need debt to have a debt crisis. 

What is debt? Debt is when a country spends too much compared to how much it earns (in case you are familiar with simple econmic terms, that is G (gov. spending) exceeds T (gov earning — $ \Delta M$ could be taken into account, is however negligible for most countries, as money printing is usually not the way to finance debt.)

"War is expensive", means that during war-time there are HUGE governmental expenses to production of weapons and what not. 
However, to say that the debt crisis is due to WW expenses one would have to look at how debt levels of Italy have developed after the world wars. 

I have found a graph in my book and saw that in the 1970 Italy had a debt ration $(\frac{B}{Y})$ of 40 percent, which in today's terms is not much, rather below average. 

In the years 1980 to 1990 Italy took up a lot of new debt, peaking at a debt level of ca. 120% in the early years of the 90's. From there debt has been 'steady' with increases to 130% in 2014. Thus, one can say. No. The debt crisis is not due to war expenses, when looking at it from this purely expense-tracking perspective...