Every major conflict has demonstrated that no nation has ever had the "right" mix of military capabilities' when defending themselves from offensive action. if they had the right capabilities they would have deterred the aggressor. I strongly believe there was no Soviet offensive in Europe during the cold war because of the huge US led NATO forces along the border.
This statement is based on a totally logical aggressor, but conflicts are rarely begun for totally logical reasons.
The statement is clearly not true for the Falklands War. Great Britain won. Great Britain had the right capabilities [would not have had a year later] The aggressor, Argentina, was not deterred.
Perhaps not "major", but big enough, and in any case I do not believe scale is significant..
Clausewitz, Machiavelli and Wellington briefed me on these matters.