With Israel expected to launch a ground offensive with elite forces, Gaza looks set to become the stage for a deadly, gruelling and very long military operation. On Friday, Israel called for civilians to evacuate from Gaza City, including United Nations personnel, to the south within 24 hours. The impact of last weekend's attack by Hamas -- the worst in Israel's history -- has left little doubt about the scale of the upcoming operation, with the intense aerial bombardment serving as preparation for a major ground assault, say analysts. They will have support from artillery, drones, fighter jets and combat helicopters.