A mistake is when something turns out wrong. In the case of the Belgrano the desired effect was achieved - we won. Not a mistake then. Not very nice perhaps, but neither was killing all those poor Germans when they set out to invade us in 1939-45.
Yes, I'd go along with those, but I'd also add the flogging off of everything else we used to own as well as the council houses.
And going to war in Iraq - that lifted the lid on the entire region, and now look at it; I fear it will get worse too.