You're not listening, carpetbagger. We talk about 'em. They're called 'traitors'.
Then after The War, they were called 'scalawags'.
But, as you know, the majority of the so called 'Southern Union soldiers' were from the border states that never seceded, or, as in the case of West Virginia, seceded twice.
The number of Southern Union soldiers understated Unionist sentiment as it was often many miles to reach the Union army and understandably many did not want to leave their families defenseless against local reb thug regimes.
On the other hand, much of the reb army was conscripted without conviction. That's why the reb armies melted away so rapidly towards the end. Most of the relatively few true believers were dead or incapacitated by then.
Even the Confederates' own laws betray a lack of national conviction. Large slaveowners got an exemption from service. Many of them couldn't tear themselves away from beating their slaves long enough to protect their own interests.