I am mostly trying to understand the historical reasoning for, what seems to me to be, the Sikh martial tradition, which primarily seems to take a defensive focus. I figured that if anything will have influenced Sikh militarisation, it would have been the empire within which most of them lived.
An additional, appreciated aside would be if you could explain how this tradition changed in the era of the Raj.
A brief search seems to indicate that the Mughal Empire and Sikhism first got their start in 1526, the notable difference being that the Mughal Empire was an Empire from the start, while Sikhism took some time to emerge as something more than a local religion. Indeed, it wasn't until 1606 that the first Sikh Guru was killed by the government, indicating that their numbers and corresponding influence was very small for up to 100 years after their appearance on the world stage.
The militarization of Sikhi stems from oppression, at that time the Mughals were invading and persecuting everyone who wasn't Muslim in North India, Sikhs answered the call, gave martyrdom, and fought from the 1500's to the 1800's. I think I've only heard of one family that fought for the Mughals and that was in the 1800's.