Question

when india got independence or when did india get independence,which on is correct ?

Answer 1

Both sentence are correct because

1."When India got independence"
This sentence is simply past indefinite
Rule-
Subject + verb2 + object

2."When did india get independence"
This is also past indefinite which follow other law of tense.
Rule -
Subject + did + verb1 + object.

I hope helped you

Answer 2

when india got Independence