Orwell writes that he had made up his mind not to shoot… what changed his mind?

The British police officer stationed in Lower Burma begins the story by commenting on his difficult authoritative position working for the imperialist regime he despises. Despite the British officer's negative feelings towards Britain's foreign policy, he must carry out his orders and deal with the difficult oppressed Burmese natives.
When the officer is initially called to handle a situation involving a loose elephant that is terrorizing the village, he does not plan on killing the animal. As the officer begins searching for the elephant, a crowd of Burmese natives begins to follow him. After witnessing the destruction caused by the elephant, the officer finds the beast peacefully eating grass on the outskirts of town. The officer says,

I had no intention of shooting the elephant—I had merely sent for the rifle to defend myself if necessary—and it is always unnerving to have a crowd following you (Orwell, 2).

However, the crowd size dramatically increases, and the Burmese natives expect the officer to shoot the elephant. The officer explains the peer pressure he feels as he stands with his rifle facing the tranquil elephant. The officer mentions,

And suddenly I realized that I should have to shoot the elephant after all. The people expected it of me and I had got to do it; I could feel their two thousand wills pressing me forward, irresistibly. And it was at this moment, as I stood there with the rifle in my hands, that I first grasped the hollowness, the futility of the white man's dominion in the East (Orwell, 3).

After the officer kills the elephant against his will, he explains the reason why he shot the beast by saying,

I often wondered whether any of the others grasped that I had done it solely to avoid looking a fool (Orwell, 4).

Orwell's insightful piece illustrates the adverse effects of colonialism on those involved, including the oppressors, who are expected to behave as resolute, callous, and authoritative individuals at all times. Overall, the British police officer kills the peaceful elephant against his will due to the peer pressure to act as an authoritative, firm extension of Britain's imperialist regime.