According to Revelation 2:10, Jesus said the church at Smyrna would have tribulation for ten days. Many things have been written about what this might mean. Some conclude it points to 10 seasons of Roman emperors, but this doesn’t seem correct to me, since at least in the case of Domitian, there is no evidence in history that he persecuted Christians. Moreover, Jesus’ ten days probably have little to do with the number of men, otherwise he might have been clearer. Why leave such a thing up to speculation?
On the other hand, some scholars seek to carve out of history a ten year period, a day for a year, where persecution against Christians was particularly severe. Yet, this, too, is largely speculative. Who is to say which period was more intense than another? Moreover, if the ten days weren’t fulfilled during the lives of the first century believers at Smyrna, what good would its reference do them be, and why would the Lord make light of their personal suffering by saying there would be a more intense persecution later? This certainly couldn’t encourage believers in the first century, nor has God ever made light of his children’s suffering elsewhere in Scripture.
Nevertheless, there are two specific 10 day periods that stand out in the word of God. They are the Jewish holy days of Leviticus 23, and they seem to have prophetic implications for mankind, especially believers. The first ten seem to point more to the trouble of Jesus, while the second ten seems to have more to do with the trouble of his disciples. Consider the seventh day Sabbath rest, which points to our rest in Jesus’ works and suffering, and Passover which points to Jesus’ crucifixion, and the Feast of Firstfruits, which pointed to Jesus’ resurrection and the Feast of Weeks, pointing to the coming of the Holy Spirit on Pentecost etc. The spring holy days were fulfilled in roughly the three and one-half year ministry of the Lord, but their effects are still felt today.
If taken just as they are written in Leviticus 23, there is a natural division between the spring and fall festivals. There were 10 days to be fulfilled in the spring, and, at the time of John’s writing of the Apocalypse, there were 10 days yet to be fulfilled, which occur in the fall. I believe the Lord pointed to these second “ten days,” which were days in the wilderness (Feast of Tabernacles), and days of want (the Day of Atonement), and the Great Day of the feast when all things would become subject to the Father etc. There are ten days in all, and the Lord seems to point out that at least some of them have to do with the tribulation of the believer. Nevertheless, Jesus tells his people to be faithful unto death (Revelation 2:10), which seems to indicate that at least some of them would die as a result of this persecution, but he also promises the faithful they would receive the “crown of life”.
 Nero (54-66 AD); Domitian (96 AD); Trajan (117 AD); Marcus Aurelius (180 AD); Severas (211 AD); Maximinius (238 AD); Decius (251 AD); Valerian (260 AD); Aurelian (275 AD); and Diocletian (305 AD).
 The 10 days are: the Sabbath, which occurs weekly, was fulfilled in the works of Christ—we are to rest in him, our Sabbath. Then comes the Passover when Jesus was crucified, plus the seven Days of Unleavened Bread, and finally Pentecost—10 days in all.
 Feast of Trumpets, which occurs on the first day of the seventh month; then comes the Day of Atonement on the 10th day, then the Feast of Tabernacles, a seven day feast, from the 15th to the 21st day, and finally the tenth day is the Last Great Day, which falls on the 22nd immediately after the Feast of Tabernacles.