Zemu had all the advanced technologies from the Fifth Dimension available for his use along with the command of his realm's armies. These technologies included, but were not limited to, interdimensional transport and weapons which could fire electro-gamma rays. These rays could liquefy solid ground and extinguish flames.
He was intent on beginning new conquests so he dispatched operatives to Earth to investigate it's potential as a likely target. Zemu's scouting party arrived in a swamp and soon discovered a housing development filled with people. Not wanting to be discovered, they sank the houses to force the people to flee. The Human Torch discovered the extradimensionals but was abducted into the Fifth Dimension before he could act. Zemu had the Torch imprisoned in a liquid chemical which left him helpless. Luckily there was an underground movement who were intent on ousting Zemo from power. Their leader, a scientist named Phineas, and his daughter Valeria freed the Torch from his imprisonment. The Torch attacked Zemu's arsenal and severely crippled his power, but Zemu's forces were still able to hold the Torch at bay using asbestos-laced ammunition. The Torch used his powers to write a call to arms in the sky which motivated Zemu's subjects to rebel. Zemu was eventually caught by the Torch, imprisoned and his people elected Phineas to succeed him.