"Was to have" expression [closed]

In 1958, Evans joined Miles Davis's sextet, where he was to have a profound influence.

What is the meaning of "was to have" here?


Quirk et al. in A Comprehensive Grammar Of The English Language (p141) list BE to as one four modal idioms, multi-word verbs that also include had better, would rather and have got to:

(d) BE to is an idiom expressing futurity, with various connotations of 'compulsion', 'plan', 'destiny', etc, according to context. In the past was to and were to express futurity from the standpoint of past time orientation.

So "In 1958, Evans joined Miles Davis's sextet, where he was to have a profound influence" can be understood simply as:

  • In 1958, Evans joined Miles Davis's sextet, where he had a profound influence.

Alternatively, you could write:

  • In 1958, Evans joined Miles Davis's sextet, where he would (go on to) have a profound influence

or

  • In 1958, Evans joined Miles Davis's sextet, where he was going to have a profound influence.

The construction to be + infinitive is one of the ways English expresses future aspect, especially when plans, schedules, or directives dictate the action. In the past tense, it can, as in your example, describe a known outcome as viewed as future from some point in the past, in this case, from 1958. The same meaning could be conveyed by:

In 1958, Evans joined Miles Davis's sextet, where he would have a profound influence.
In 1958, Evans joined Miles Davis's sextet, where he was going to have a profound influence.

The same notion of time informs this sentence about building a railway:

The Pacific railway was to be a government project, but it was to be built by private companies supported by government aid. — Encyclopedia of North American Railroads, 2007, 796.

Railway construction was planned and executed as a public-private partnership. Narrative time lies before the construction took place.

In the present tense, the construction can have the force of an imperative with no particular anchor to time, especially in formulating rules, regulations, or directives, for instance, in these sentences excerpted from rules governing construction sites in an Oklahoma town:

Sand, mud, and debris that enter the roadway are to be immediately cleaned up and placed back onto the construction site.
Maintain an on-site receptacle for depositing trash and debris. The receptacle is to be at a standard capable of restricting trash and debris from blowing onto adjacent properties.
Trash and debris is to be cleaned daily, contained on-site and disposed of in a waste receptacle to prevent wind or rain from carrying it off-site into a storm drain or waterway.
A copy of the permit and temporary address sign indicating the street number are to be posted in the front of the property near the street or road. These are to be clearly visible and maintained for the duration of the construction period. — Building Permit Requirements, City of Jenks (OK), 26 Mar. 2018.

This construction can also be used when a planned event does not take place:

The atmosphere inside a coating tank was tested and ventilated the day before work was to be performed. — U.S. Chemical Safety and Hazard Investigation Board, Hazards of Nitrogen Asphyxiation, June 2003.

Work on the tank was scheduled on the day after testing and ventilation, but there was a fatal accident, so the work was not performed as scheduled.

Last week, Warner Bros. canceled a town hall scheduled for March 15 that was to have been led by Tsujihara in something of a victory lap after his recent promotion. The move was so abrupt that flyers for the event still could be found on the Burbank lot a day before it was to have taken place. The town hall has since been rescheduled for April. — Hollywood Reporter, 18 Mar. 2019.

In this sentence, the perfect infinitive (to have been led, to have taken place) accentuates on 18 Mar. the recent past of 15 Mar., when a planned event didn’t happen but would have had not other forces intervened. The executive was fired for trying to get parts for an actress with whom he had been having an affair.