[The Battle of] Rocroi shattered the myth of invincibility of the Spanish tercios, the pike and shot infantry units that had dominated European battlefields for the previous 120 years. The battle is therefore often considered to mark the end of Spanish military greatness and the beginning of French hegemony in Europe during the 17th century.[7] After Rocroi, the Spanish progressively transformed the tercio system incorporating more of the line infantry doctrine used by the French over time.[8][7]

https://en.wikipedia.org/wiki/Battle_of_Rocroi

wikipedia has an article about this painting, but only in Spanish: https://es.wikipedia.org/wiki/Rocroi,_el_último_tercio auto-translate works pretty well tho the word “tercio” is usually not translated, e.g.: https://en.wikipedia.org/wiki/Tercio Interestingly it was only recently painted, in 2011.