On December 21, 1887, British Prime Minister Gladstone publicly declared war on Afghanistan in response to inquiries from Parliament, thus igniting the Second Anglo-Afghan War.
At that time, the Great Britain Empire could bully a small nation without the need for parliamentary authorization. In fact, had it not been for the uproar caused by the Walters assassination case, Afghanistan would not even have qualified to be formally declared war upon.
Like most native tribes of the era, the Afghan Government was never recognized by the European world.
In the eyes of most Europeans, the Country of Afghanistan was little different from a native tribe. Even though the British Army had been defeated in the previous Afghan war, it did not change outsiders' perceptions.
Because the Indian Colonial Army could not represent Britannia's true combat strength, and it was the East India Company, not the entire Great Britain Empire, that fought Afghanistan.