Dao was a human who served as an admiral – a rank – in the Galactic Republic's naval branch during the Clone Wars conflict.
In the year 22 BBY, Dao took part in a planetary engagement over the world of Ryloth, where he commanded a Republic Star Destroyer fleet that was intended to provide relief. During this particular battle, the Republic officer and his fleet made an attempt to fight off a blockade comprised of warships from the Separatist Alliance. These Separatist vessels were under the command of Neimoidian Captain Mar Tuuk, and were positioned in orbit around Ryloth.
During the course of this battle, the Republic officer's forces found themselves with critically depleted supplies and were unable to provide assistance to Jedi General Ima-Gun Di's forces on the planet's surface. Shortly after this, Dao was killed during a conversation with members of the Jedi High Council, when his Star Destroyer was destroyed by an explosion. Dao's death led to the Separatist blockade successfully establishing a planetary defense in orbit, while Di's ground forces continued their fight against the Separatist Droid Army below.
Dao wore the standard military uniforms common among officers of the Republic's military. His uniform also included a insignia plaque displaying three red squares and two blue squares, which indicated his rank of admiral.
Dao's first appearance was in "Supply Lines," which was the third episode of third season of the Star Wars: The Clone Wars animated television series. This episode was originally broadcast on September 24, 2010. James Arnold Taylor provided the voice for the character, and he also voiced Obi-Wan Kenobi in the same series.