What was the motivation behind building Dongnimmun (Independence Gate)?

Dongnimmun was not about resisting Japan,
but about gaining independence from the Qing Dynasty.
It was built 13 years before the loss of national sovereignty in 1910.
Since the Manchu invasion of Korea, King Injo had to surrender at Samjeondo,
and the country lived as a vassal state of the Qing Dynasty.