Hi David
   The Rapture is before the seven year tribulation period. At the day
of Christ we are raptured up to Him for our rewards at the Bema/
judgment seat of Christ.
   The "Day of the Lord" referenced here is the second coming. The
context here is that during the Tribulation period, there will be a
brief time of pseudo-peace after the antichrist rides forth, when
people will be able to take a breath saying "Peace and Safety." Then
all of a Sudden, The Rider on the Red Horse, the second seal, comes
forth and the global war all have feared begins, lasting
intermittently through the rest of the tribulation period ... which
ends at Armageddon, the Day of the Lord.
Lewis B