I highly recommend you re read your history.
Not bollywood history, but real history.
The Sikh Kingdom was one of the last independent kingdoms to be conquered by the British. And the British did it with HINDU troops. So Sikhs were not happy about that. So when some of the Hindus (and Muslims) rebelled in the 1853 rebellion, the British used Sikh troops to bring them in order. The reason they used Sikh troops was because the Sikhs wanted to settle the score with the Hindus.
You can romanticize it all you want but the fact is that in most of Indian history there was never any real unity. Hindus, Muslims, Sikhs were all fighting with each other. that's why the Brits had such an easy time conquering us.
Thats not true,
The differences of Opinion between Hindus and Sikhs and the differences between Muslims vis a vis are too different in nature.Not one and the same.