1) world building-introduce rebel as a foal in the southern part of equestria, the son of a slave master working on an APPLE plantation, in his youth fully aware of the horrors and lifes of slaves but ala huck finn simply not questioning it, it's simply how things were. If not serve ponies what would zebras even do with themselves and after all it's legal so it must be ok
if I pace this properly this should be about 2-3 thousand words progressing his life from foal about the age of applebloom to the outbreak of the war and his conscription
2) I'd tell of his minimal training for the war effort, how earth ponies like himself were only given their hooves and maybe a saber to fight how the southern forces lived in constant fear of the unicorn artillery how pegasi rained hail and lightening from the skies but how still he and his kind fought on. In his mind and those of his brothers in arms this war was of those with wealth and power, those who had everything they could want trying to take away the only thing they could cling to, their freedom by taking our their right to property they'd start a chain that'd leave them as nothing more than slaves themselves
3) I'd tell of his first real rout, running for his life away from the better armed, fed, and trained northern forces. Seeing his closet friend struck down by lightening not even 3 feet from him watching his CO literally explode as he's hit by a well aimed spell, how he does the only thing he can, he hides in the cellar of the nearby plantation house, the owner long gone before the battle his slave along with him, he'd stay closer to the shutter looking through the cracks in the boards watching for any signs of movement, staying there for what must be hours before he finally looks behind him, taking in the dank cellar and finding a young zebra cowering away from him in a back corner deathly afraid of him not only due to the blood covering him, but from the dingy uniform he wore signifying him as fighting against her own freedom
4) some shit happens I haven't planned out at all yet, many feels, romance happens, rebel has multiple meanings, so clop happens, sad or happy end idk