Summary
Captain of the UNSC Commonwealth. Wallace lost his left arm below the elbow some time in his career. Rather than utilize an artificial limb, he simply did not have a left arm, something that probably too getting used to by his crew.
Wallace was rather by-the-book and did not enjoy having civilians on his bridge, as evidenced by his displeasure of Dr. Catherine Halsey.
In 2525, Wallace was instrumental in helping the Spartans criple a Covenant frigate enough for them to destroy it.