The future in the past is a grammatical tense where the time reference is in the future with respect to a vantage point that is itself in the past.
In English, future in the past is not always considered a separate tense, but rather as either a subcategory of future[1] or past[2] tense and is typically used in narrations of past events: John left for the front; he would not return until five years later.
The future in the past may also be commonly used for indirect speech (She said she would return), and it often has a modal aspect to its meaning.
Besides English, the future in the past is also found in Bulgarian and a number of other languages.
Here, an event is situated before a reference point, which in turn is in the future relative to another point in the past:John left for the front; by the time he should return, the fields would have been burnt to stubble.Besides English, the future perfect in the past is also found in Bulgarian.