Twila,
A long answer to your question regarding when Drew's Regt began to defect.

Of course, each individual could describe or "justify" his actions in any number of ways. The personal view you describe is reasonable for some individuals but probably not the majority view. Drew's Regt did provide a "bodyguard" for Ross but it was not the role of the regiment.

Drew's Regiment viewed themselves as "homeguards" whose role was to protect the Cherokee Nation from any invaders. This included, of course, protection of the Cherokee government and the principal chief. The biggest threat at the time was from outlaws, particularly Kansas jayhawkers. While the Keetoowah harbored much hatred for Watie and his new regiment, they knew their was a treaty with the Confederacy and they saw Ross and Watie shake hands in Tahlequah when the treaty was signed.

Drew's men did not expect to be asked to fight on behalf of the Confederacy and they certainly didn't expect to fight the other Indian Nations.

The first assignment of Drew's regiment was to move to Coodey's Bluff (just east of present Nowata) and spread out to protect the northern settlements from Kansas jayhawkers. The jayhawkers were stealing cattle and even taking prisoners in the Cooweescoowee District.

In December 1861, Drew's Regt was sent to join with the rest of Col D H Cooper's command to force Opothleyahola to submit to Creek law (that is, the Creek treaty with the Confederacy) or destroy his force. Cooper didn't know that it was Keetoowah of Drew's Regt that invited Opothleyahola into the Cherokee Nation in the first place. A large number of Drew's Regt went AWOL before the battle on Bird Creek -- some fought on the side of Opothleyahola and some left and went to Ft Gibson. Of those that fought on the side of Opothleyahola, some returned to Drew's Regt and some stayed with Opothleyahola's band and eventually made it to Kansas.

There were members of Watie's Regt that wanted Ross out of office but Ross's life was probably not in jeopardy from Watie's men until the mass defection of Drew's Regt after Locust Grove (July '62). Many of Drew's Regt defected immediately after the Locust Grove affair but others retreated to Ross's home at Park Hill. Union Capt Harris Greeno arrived at Park Hill where he found Keetoowah of Drew's Regt camped around Ross's home. Ross had just received a request to call up all Cherokee of fighting age to oppose the Union Indian Expedition. Greeno "declared" those of Drew's Regt, which included most of the officers, prisoners-of-war and escorted them back to the Union camp where they were enrolled in the 2nd and 3rd Indian Home Guard (Union). Greeno also "declared" Ross as prisoner and paroled him at his home. Some Pins remained with Ross to protect him from Watie's Regt and other Confederates. About three weeks later, in early August, Union Col. Cloud arrived in Park Hill and escorted Ross and others (and the Cherokee Treasury), north to Kansas. At this time, the remainder of the Pins of Drew's Regt joined the Union Army. (There were undoubtedly some Keetoowah who just went home to protect their families.) There were only 50-75 of Drew's Regt that remained loyal to the Confederacy but the regiment itself ceased to exist.