From Wikipedia about the first battle:
On April 18, 1648, around forty five hundred Dutch soldiers and five artillery pieces marched south, coming from Recife. On their way south, they eliminated a small defensive outpost on the village of Barreta. The few survivors regrouped at the village of Arraial Novo do Bom Jesus, headquarters of the Pernambucana resistance, where they reported the incident.4,500 men? The Netherlands didn't have but two million people at that time. That is a huge commitment of their available adult male population.
I just recently finished The Shipwrecked Men by Álvar Núñez Cabeza de Vaca, an account of the 1527 Narváez expedition which started in Florida with some 500-600 men. Eight years later, Cabeza de Vaca with three other surviving Spaniards made it to Mexico City, having travelled across the Southeastern US and likely much of the southwest (their route being uncertain).
A fascinating era of discovery and exploration.