A later UNSC fleet at Reach: winning a battle versus ending a war

What if the entire post-Human-Covenant War UNSC navy arrived at the height of the Battle of Reach?

The reinforced UNSC is expected to win the battle, but the wider war and the effects of the crews' future knowledge remain unsettled.

In the Halo scenario, the postwar UNSC fleet arrives during the Battle of Reach, before the later crises involving Cortana and the Banished. Infinity and other surviving heavy ships would substantially reinforce the defenders. The fleet total is uncertain, with estimates varying widely, but the combined force is judged capable of winning the immediate battle. That would still leave a much larger Covenant war effort to confront. Losses and industrial recovery could delay the next Covenant concentration, while knowledge carried back by the later crews would create political friction over ONI's conduct. These are in-universe assumptions, and the battle result does not by itself settle the war.