A short article about Veteran’s Day parades in the Sacramento, California area also references the role of Sikh soldiers in the two world wars:

Sikh pioneers who came to America in the beginning of twentieth century were mostly veterans of World War 1. 83000 Sikh soldiers died fighting for Allied forces in two World Wars. Their memorials were erected in many European countries such as France, Netherlands, and Britain.

One historic item that is not well known is that  there were Sikhs (and other Indians) who also fought alongside the Nazi Germans during World War II.  Their motive was to fight against the British to free the then British-ruled India, so Germany was a convenient ally for some Indian freedom fighters.