Before large "National Armies" became the norm, governments hired Mercenary Armies. Soldering was a profession and certain nationalities had their specialties:

The Best Pikemen were Swiss Mercenaries.

(Ironically, the best crossbow men came from Genoa, Italy).

..... and God help you if you were slow or unable to pay your hired troops.
(It was also a pain to get rid of them after your war).