It was the last old fashioned war. The modern technology that put an end to that kind of fighting had already been invented, but was not used by either side.
In WWI, only sixteen years later, they used powerful machine guns that fired hundreds of rounds a minute. Say goodbye to cavalry charges!
It was a mix, with us being on the short end. Spanish troops has 5-shot magazine-fed 7MM Mauser rifles, we had single shot 45-70 black powder rifles or 30-40 loose ammo Krag rifles; they had Maxim machine guns, we had Gatling guns; they had lousy leadership, we had somewhat better.