That time etc. etc. slime (too long title)
After having more or less genocided the Ogres, the Orc horde enters the swamp lands of the Lizardmen. Fortunately, the one of them with a bit of brain is their king and he orders his son, Gabiru (who has no brain), to leave their village with a Lizardman army and recruit allies amongst the neighbouring people, mostly Goblins, to help with the fight against the Orc horde. He does that for a while, straining his intellect to the bursting point in doing so. His warriors are no less intellectually challenge and start goading him into seizing power, because... he's such a great warrior, a hero and a genius, much better at everything than his dad, the king. If anyone has see The Fifth Element, it was like a throwback to Ruby Rhod and the way his sycophants were fawning all over him. I can't remember if I mentioned it before, but he really is smarter, stronger and faster than his warriors, because he got a name bestowed upon him by Lord Gelmud (who we know nothing about at this point except he also has a master whose bidding he's doing).
Some particularly hilarious scenes has Gabiru basking in sunlight beams, reflected off the shields of his warriors (who points the light towards their hero), looking like a movie star posing for the cameras... 😂
Eventually believing his own delusions, he deposes of his father the king and decides to round up Rimuru's village as "cannon fodder", in addition to the 7000 goblins he already conscripted for the glorious nation of the Lizardmen.
Tl;dr; it didn't go to plan and his unconscious form gets carried off by his warriors. However, Rimuru has come to the conclusion (well, not really by himself, but a visit of a Dryad, the caretaker of the forest convinced him) that the Orc Lord and his horde (200000 strong) needs to be dealt with.
Gathering his villages and the 6 Kijin (ex-Ogres), he and his army squares off against the Orc army. Rimuru doesn't even get to flex any of his magic muscles as between them, the 6 Kijin annihilates a quarter of the Orc army and forces a confrontation between the Orc Lord and Rimuru.
To make a long and epic battle short, Rimuru is victorious and the Orc Lord is mortally wounded. From the dying Orc Lord, Rimuru learns a bit of exposition, who the Orc Lord was before he was given a name and why he was found dying in a wasteland by Lord Gelmud. A long and devastating famine had threatened to wipe out of the Orcs, dying a slow and painful death from starvation. Gelmud used this by bestowing a new ability on the Orc Lord, who could pass it on to his people. Similar to Rimuru, Orcs can (or could, the ability got consumed by Rimuru when defeating the Orc Lord) eat not only dead enemies, but their own dead and so sustain themselves, even growing stronger and absorbing the strength of the fallen they eat. Basically turning them into an almost mindless horde of ravenous, all consuming swarm of land sharks.... but, Rimuru offers the surviving Orcs, that they can join his village. They get food and shelter in return for providing muscle and labour to they growing community.
Some time during the battle with the Ord Lord (named 'Geld'), Lord Gelmud had stressful experience where his head got separated permanently from his body....
Last thing to do, Rimuru frees the Lizardman king from captivity and they enter an alliance. At a gathering, they all declare Rimuru "Grand Chancellor of The Great Forest of Jura" (with the Dryad's blessing).
A few hints and about what was going on before, including Lord Gelmud's master, but not much info yet.
Gabiru gets sentence exile (much to his surprise, as he was convinced he was going to die) by his father, the king. Three of his closest syco... followers are overjoyed, knowing that he'll survive, and decides to follow him into exile.