No invasion. Tennessee's properly elected legislature decided to secede and called the referendum. Nor was there a previous secession vote to "revise" as you dishonestly suggest. The only previous referendum was on whether or not to call a convention on the matter of secession. Tennessee voted against it basically as the state split into three regions. The west was adamantly pro-secession from the start and remained so through both elections. Some counties there were even so strong on it that they demanded the ability to secede from Tennessee and join Alabama or Mississippi if the legislature would not act. The east was anti-secession and remained so through both elections (they voted against it in the secession referendum despite your unsubstantiated claims about armed guards forcing them to do otherwise). The swing area was in middle Tennessee, which was marginally against secession at the convention vote but had shifted its opinion in favor of secession after Fort Sumter. The referendum passed due to that shift in opinion, not some armed guard making everybody vote for it.
Following that was the initiation of these sorts of brutal guerilla warfare tactics by the bastard scum slavers.
Quod gratis asseritur, gratis negatur. While comparatively little evidence exists of confederate brutality prior to Milroy's arrival, acts of mass murder and torture by yankee-commissioned guerillas in Tennessee extend throughout the war. The most notorious was yankee Col. Fielding Hurst. He operated from August 1862 through the end of the war, committing vile brutalities throughout. In mid-1863 Hurst's band of thugs captured some confederate POW's, proceded to hack off their heads, and placed them on stakes as mile markers along a road. These and other actions prompted some of Hurst's superiors to urge that he be penalized but the yankee command instead gave him a roving commission to continue his operations that December. Hurst kicked off the new year by having his men capture a physically handicapped child and beat him to death. A few weeks later they executed some more POW's and displayed the corpses in public for a week, allowing them to rot and denying burial. Executions of this sort continued every couple of weeks for the remainder of the year and often involved the prisoners being removed in the middle of the night and their brutalized bodies being discovered the next morning in the woods. In the spring of 1864 his men captured a confederate Lieutenant who was home on furlough. They dragged him from his home in the middle of the night, took him into the woods for torture, skinned his face while he was alive, shot him, and mutlilated the body. This was common for his victims. He often cut out their tongues, eyes, and genitals while they were still alive and then ended it with a shot to the head. At one point Forrest even sent a letter to the yankee command demanding the surrender of Hurst and his men to be prosecuted for their war crimes. The yankees refused and claimed that Hurst had been acting properly.
By the time Milroy got there, it was just a matter of returning the faover
No he wasn't. He was simply continuing what Hurst had started three years earlier. Hurst resigned his commission for health reasons in December 1864, just after Milroy arrived. Milroy's death lists were in circulation by January and continued for the next several months.
In fact, your woebegone ancestors probably didn't have a metal spoon in the house
False. Milroy's death list specifically ordered the yankees to steal all the spoons, as well as other furniture, from his house. They all include detailed lists of valuables to loot for each house. Mine also apparently had a lot of guns because the note next to his name specifically directs the yankees to confiscate those as well.