Complex sentence: The city was founded on 24 June 1478, with the name "Real de Las Palmas" by Juan Rejón, head of the invading Castilian army, before engaging in war with the local Guanches (aboriginal people of the Canary Islands).
Split into simpler sentences: The city was founded by Juan Rejón on 24 June 1478, with the name "Real de Las Palmas". Rejón was head of the invading Castilian army, before engaging in war with the local Guanches (aboriginal people of the Canary Islands).