Welcome to Halo Answers. What would you like to know?

Because the covenant hadn't developed the phantom during the time period in which Halo Wars takes place.

^Actually, the first Phantom was sighted in 2531, the same year that Halo Wars takes place. It's possible, though, that the Covenant did not widely issue the Phantom as of yet, and/or they were reserved for use by certain units or VIPs.

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.