There are sadly very few Velazquez drawings that survived the centuries that have passed since his career took hold in the Spanish Golden Age. Therefore, it is difficult to put this particular drawing within any great context or compare it to any related artworks.
Artist Velaquez had a strong connection to several members of the Spanish conquerers and for this reason put a great importance on the final painting. Several key generals on both sides of the battle were highly respected and suitable for depiction by such a prestigious artist.
Close companion General Spinola is the figure outlined here, clearly a critical of the final composition and something Velazquez was prepared to practice repeatedly until he was contented with that element.
Spinola himself was seen as an honourable man, fierce in battle but highly respectful in victory or defeat. He would order his controlling army to behave fairly to the defeated Dutch and promote a cordial atmosphere. This was in contrast to many situations during this period of European conflict, typified by the Thirty Years War.
The Spanish Golden Age itself featured far more than just oil painting, covering literature, exploration and architecture too. Amongst the artists were also El Greco (Greek, who famously settled in Toledo), Francisco de Zurbaran and Bartolome Esteban Murillo.
The massively influential Spanish artist who also covered battle scenes within his work was Francisco de Goya, who followed on some two centuries after the achievements of the likes of Diego Velazquez and the other early Spanish Baroque painters.