The Confederacy did use a lot of gurellia warfare during the Civil War and it arguably caused more suffering to the South than success.

As the Mississippi River was being opened up by the Union army and Navy, a lot of boats were attacked by snipers and in some cases set fire to. To respond, the Navy and army didn't go after the snipper, they used cannons and blasted the towns on the river right next to the incident, figuring that is the town where the assailant came from. In cases where attacks were common, troops went in and burned down the entire town. This happened in several places and was effective in ending the attacks in the boats but obviously had a severe impact on civilians.

Sherman was a subordinate general at that time and eventually managed Memphis and the navigability of the river. He learned from that experience. Once the full Mississippi was secured, Sherman's next mission was to head eastward. Eventually through Georgia and the Carolinas. Wherever he went, his orders to his troops was to leave towns that submitted peacefully alone but for towns that fought gurellia warfare against Union troops faced a lot of destruction.

Atlanta was heavily burned where those businesses contributed to the war.

When land mines were laid in front of Sherman's troops on the March to the Sea, he used Confederate POW's to clear them.

When his troops freed Union soldiers at a POW camp and realised it was basically operated as a death camp, they burned the town near by. (This was a different camp than Andersonville)

Columbia was mostly destroyed by Sherman's troops for starting the war.

In this entire Campaign, Sherman was tasked to go after a major army (Johnston's) but instead avoided a major engagement and just basically had his way with the South. He purposely wrecked devastation against the civilian homes who caused and supported the war. (This was burning of buildings rather than the murder of civilians.). He knew the Southern people very well and purposely chose this method to win the war.

The effect of this campaign was extraordinarily successful in the bigger picture. With minimal loss of army and civilian lives, Confederate moral and war making capabilities were devastated.

Southerners had been happy to fight with Lee up North but while their homes and families were safe. But when all of that was being destroyed, it lead tens of thousands of Confederates to quit the war and walk home.

Sherman was headed straight North towards Lee and it was clear the Union would win. What was also clear was that Sherman's troops would burn every last home and business in the South if that is what it would take to secure peace.

So, in summary, that gurellia warfare isn't a winning strategy against an army who doesn't have its hands tied.

A recent biography of Sherman by James McDonough covered all of this and is a great read.

They had neither the reason nor the ability to do so. The Confederacy wanted to be accepted into the global community of nations, and there would be no way to do that if Lee disbanded his army to fight as guerrillas. To reach that objective, the Confederacy would have to function like a modern nation -it had to control its territory, enforce law and policy, and maintain a regular army. By the time of Appomattox, that was an impossibility.

The justification Edward Porter Alexander, the finest artilleryman in the Army of Northern Virginia, supplies as a response by Lee to his suggestion that the army disband, whether to fight as guerrillas or to rejoin Johnston's army in North Carolina, was that there was no point in it. It would simply prolong the war, and while it might sound fine for strong young men to go bushwhacking, their country needed them to help rebuild. If they insist on uselessly prolonging the war, it would simply bring ruin and pillage to places of the South that had previously escaped it, but that if he could secure paroles for his men, they could return home in time for the spring planting season, and get the country back on its feet.

It's important to remember, too, that the Confederacy was more or less spent by 1865. More than 90% of all military aged men had been mobilized, and in terms of military dead as a percentage of population, the Confederacy lost more men than the Soviet Union in WWII. The men who were still alive in 1865 couldn't be supplied; the U.S. Army calculates that a man in combat conditions needs 4000 calories to maintain muscle mass every day; the Confederate infantryman during that tortuous final march from Richmond-Petersburg to Appomattox was getting just nine hundred a day. While the Union gave its horses twenty five pounds of feed a day, Confederate horses were getting two.

With nothing left to fight with, I have grace doubts the South could have outlasted the North past that point. The North won because the three main field forces of the Confederacy (the Army of Vicksburg, the Army of Tennessee, and finally the Army of Northern Virginia) were at last defeated, despite the South having put everything their nation had to offer behind them.