Someone, unbeknownst to the Commander, spiked Commander Vorik's beer with an invisibility potion. There was a brief moment of panic in the tavern as their commander just up and disappeared. However all was calmed when he assured everyone, he was indeed, there. Albeit, invisible.
At first it was a minor annoyance for the commander. However it was overridden by the sheer usefulness of invisibility. Guards are now on high alert as the rumor spreads, and adventurers and townfolk alike have caught the Commander barking invisible orders to guards kept lazing about and snoozing on the job.
The Militia has turned paranoid, as now their Commander could be anywhere.