Halo 3 Question

[Tbh.]

Spartan Officer [25]
Advance to the Spartan Officer ranks (Online).

which game type/mode do i have to play to get this
and what exactly do i need to do?

i dont play halo often so im not really sure on how to get this

[Trinity]

I very rarely play Halo, but I think this will help - http://halo.wikia.com/wiki/Spartan_Officer

[Tbh.]

I very rarely play Halo, but I think this will help - http://halo.wikia.com/wiki/Spartan_Officer

Thank you (:
xx

[Trinity]

Thank you (:
xx

You're welcome :)