What effect did the panther likeclashing of the two armies have upon Henry?

"His mind flew in all directions. He conceived the two armies to be at each other panther fashion. He listened for a time. Then he began to run in the direction of the battle. He saw that it was an ironical thing for him to be running thus toward that which he had been at such pains to avoid. But he said, in substance, to himself that if the earth and the moon were about to clash, many persons would doubtless plan to get upon the roofs to witness the collision."

Henry had been moving away from the battle; he's afraid and unsure. The 'panther' like description, shows two opposing groups of men who are what I believe to be 'circling,' ready to 'pounce,' 'stalking' each other. The effect it has on Henry is to make him curious; he's no longer a part of the battle, but he wants to bear witness like a spectator. His comparison to the many people who would 'get upon the roofs' can be likened to people today gawking at the accident on the side of the road or going outside to stand on the sidewalk when an ambulance pulls down the street. People don't want to get involved, but they do want to see what's happening.