How is the seven-year tribulation period divided according to Daniel?

Daniel's prophecy divides the seven-year covenant week into two equal halves at the middle of the week. The first three and a half years come first, followed by the last three and a half years. This midpoint provides the format for the tribulation period, with the Antichrist confirming a covenant for the full seven years.

Les teaches that in Daniel 9:27 the prophecy turns to the one week, and the Antichrist, identified as the prince that shall come in verse 26, will confirm or make a treaty or covenant with Israel for one week, that is seven years. In the middle of the week, Daniel has already, by inspiration, laid out the format that this seven-year period is going to be divided in half: there will be the first three and a half years, and then the last three and a half years. Les cautions against calling the first half a time of real peace and prosperity, because it will be short-lived. For a little while it may seem as though the Antichrist is keeping his word, bringing peace and prosperity. Israel will enjoy again her temple worship, and she will enjoy fear from her outside enemies. But then, as previously studied, that condition does not last.

Why is the middle of Daniel's seven-year week important for understanding the tribulation?

The middle of Daniel’s seven-year week divides that covenant period into two equal halves of three and a half years each. That midpoint is the basis for teaching about the tribulation, because Daniel by inspiration lays out the format that the seven years are split in half.