For the most part, these things have not happened yet, but will, and perhaps very soon and suddenly. The seals in Revelation are broken in order, but the effects are likely overlapping and not immediate. Read Revelation 6 & 7 thoughtfully, and compare it with Matthew 24 and 1st and 2nd Thessalonians. There is a general ordering of events which is consistent. We can discuss in length, but the 5th seal emphasizes the martyring of the saints. The 6th seal is the sign of the LORD's immanent return. That is when the world realizes its time is up. The next two things that happen are the sealing of the 144,000, and the sudden appearance of a great multitude in heaven (rapture). Then the 7th seal is broken which initiates the Day of the LORD judgment upon the earth. The 144,000 are sealed (protected) because they are left behind when the rapture happens. As Jesus says in Matthew 24, the Great Tribulation begins with the Abomination of Desolation (AoD) at the mid-point of Daniel's 70th week (see Matt. 24:15-26). (As a note, Matt. 5-14 are a general overview of when the end will come; but beginning at verse 15 Jesus steps back into this overview to provide more detail.) Now if you read verses 27-31, it describes the sign of His coming which all shall see (sun, moon, and stars - compare to description of breaking of 6th seal), then in verse 31 it describes the rapture (compare to great multitude appearing after breaking of 6th seal). Paul, in 2nd Thess., likewise mentions that the Day of the LORD (when He comes for us) will not happen until after the revealing of the son of perdition and the falling away which will ensue. This all fits very nicely together, if one is willing to see it. The problem is, most are unwilling to look because it is too scary. They want the promise of an easy escape and eternal security. They don't want to be told that things could get really hard and that they might have to make a really hard choice - like between physical life or eternal life - this is why it is called the Great Tribulation. It will be a time of untold suffering and persecution, but most churches refuse to teach this - or they make it out that we will all get sucked outta here before all this poop hits the fan.