We may not look the part, but we actually were a national capital. So nener-nener-nener.
May 22, 1855 - February 16, 1934.
If you twist the truth a little, you can stretch it out to:
October 14, 1832 - March 31, 1949.
But only if you accept we were a nation under Representative Government (1832-1855, locally elected Parliament led by Governor appointed by London) and Commission of Government (1934-1949, direct rule from London, but with the continued status in name only of an independent country) .