How is the process of unification of Spain similar to the process of unification of France or Japan? What are the differences?

In Spain, as in France, the unification of the country demanded that the kings suppress the highest aristocracy. However, in France it is. happened after the unification of the country (in the wars of Louis XI), and in Spain – before that (in the Castilian strife during the youth of Queen Isabella). One of the reasons for this difference is the intense struggle between the Spaniards and the Muslims, which ended successfully only after the victory of Fernando and Isabella over the rebellious nobility of Castile.
The unification of Japan, like the unification of France, took place in the absence of a strong external enemy. In Spain, Muslims were such an enemy, so the state structure of a united Spain is more “monarchical” than the structure of a united Japan.

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