Question

What purpose the cantonment area serve before the partition of sub-continent​

Answer 1

The word cantonment, derived from the French word canton, meaning corner or district, refers to a temporary military or winter encampment. For example, at the start of the Waterloo campaign in 1815, while the Duke of Wellington's headquarters were in Brussels, most of his Anglo–allied army of 93,000 soldiers were cantoned, or stationed, to the south of Brussels.

hope it helps you