the only reason why you couldn't simply shoot the human army was because the crossbows the rangers wielded had a longer range than your own bows. If you could deal with the crossbowmen, you could outrun the army indefinitely and pelt them with projectiles! You shout to the other Centaurs who followed you, "kill as many of the crossbowmen as you can, do not engage with the footmen." They all nod in approval, thankful that they wouldn't have to fight the nigh-Impenetrable wall of shields and swords. After making sure they understood you, you order a charge. The Centaurs eagerly follow your leadership, and the thunder of hoofbeats echoes through the land once again.
The crossbowmen scream for the army to prepare for a rear charge. The back rank turn around to face you, giving the Centaurs engaged in melee some respite. They place their shields on the ground facing you, with long spears menacing through the gaps. The crossbowmen run parallel to the shields to get out of the way of your charge. They fully expected you to stupidly run yourself into the spears. But to their horror, your charge splits down the middle, with half going left, and half going right. The crossbowmen try to run inside the formation, but the locked shields prevent their retreat. You and the others skewer, trample, and slash every last crossbowmen as they flee from your charge. A few crossbowmen survived the charge, but their numbers were so small it was inconsequential.
You shout to Erelibos to disengage. "The rangers are dead! Disengage!" Erelibos was so caught up in the fighting that it took his mind some time to process your command, but he quickly sees the sense in your order, and he gives the order to his melee fighters. Slowly, the Centaurs disengage, some galloping away, others limping. Erelibos is the last to make it clear of the army, but right before he makes it clear, he trips on a dead Centaur and falls. The soldiers begin raining blows onto his body, the blows sending sparks off of his dwarven-crafted armor. It was only a matter of time before a strike Guyana weak point, and soldiers were pinning him to the ground, so that he couldn't get up. The rest of the soldiers reformed their shield-wall placing shields in front and on top, facing you and the disengaging Centaurs. You wanted to help, but the entire Human army was in your way.