would is the everyday way to look forward from a moment in the past — at that time, the thing still lay ahead. Use would + the base verb, most often when you report what someone knew, thought, said, or promised. It carries no extra flavor — no plan, no schedule, no ceremony — just "from then, this was still to come". For something already finished by that later point, use would have + the past participle.
would + verb (looking ahead from the past)
She had no idea that day would change her life.
He knew he would regret those words.
They promised the letter would arrive by Friday.
Not "She knew she will win the prize." — say "She knew she would win the prize.". After a past reporting verb like "knew", the future shifts back: will becomes would.
Try it: Before the vote, he told the crowd that history ___ remember the day. (would / will / is going to) Answer: would — Reported from a past moment ("he told the crowd"), the future shifts back: will becomes would remember. "Will" keeps a present viewpoint, but the sentence looks forward from the past. "Is going to" is also present-viewpoint and hints at a plan already in motion, which doesn't fit a prediction about history.
was / were going to + verb
To talk about a plan or intention you held at a past point — whether or not it happened — use was / were going to + the base verb. It is the past of "is going to", and it very often sets up a plan that then fell through: "I was going to call, but ...". In speech you can even leave the verb out once it is clear: "I meant to — I really was going to." Register is neutral and everyday. Negative: wasn't / weren't going to.
She was going to accept the offer, but changed her mind.
They were going to visit Senfarren, but the trip was canceled.
I was going to call you — then your message arrived.
Not "Yesterday she is going to accept, but didn't." — say "Yesterday she was going to accept, but didn't.". You are looking back from now, so use the past was going to, not "is going to".
Try it: We ___ leave at dawn, but the storm forced us to wait. (were going to / are going to / will) Answer: were going to — This is a plan held at a past point that did not happen, so use the past form: were going to leave. "Are going to" describes a plan happening now, but this looks back at one that fell through. "Will" points forward from now, not back at a past intention.
was / were due to + verb (a scheduled time)
For something scheduled for a set time, seen from the past, use was / were due to + the base verb. It points at a fixed slot on a timetable, calendar, or plan — a train, a meeting, a delivery — not a personal wish. The to never drops. Negative: wasn't / weren't due to. For a scheduled thing that then did not happen, use was due to have + the past participle: "The report was due to have been published in May."
The flight was due to depart at 14:00, but fog delayed it.
Delegates were due to arrive on Monday.
The results were due to be announced at noon.
Not "The train was due leave at nine." — say "The train was due to leave at nine.". "due to" always keeps its to before the base verb — never "was due leave".
Try it: The ferry ___ at six, but engine trouble kept it in port. (was due to sail / was due sail / is due to sail) Answer: was due to sail — A fixed, scheduled time seen from the past takes was due to + the base verb: was due to sail. "Was due sail" drops the to that "due to" always keeps. "Is due to sail" is the present-viewpoint version, but the rest of the sentence ("kept it in port") looks back, so it needs the past was due to.
was / were to + verb
Was / were to + the base verb does two related jobs, and it is worth keeping them apart. (1) A formal arrangement: "The ceremony was to be held at noon" says it was scheduled, and leaves open whether it happened — for one that fell through, use was to have + the past participle ("The summit was to have been held in Vienna"). (2) An appointed course of events looking back from a later vantage point: "The discovery was to become famous" says it did become famous. Either way this is a formal, written register — the voice of reports, histories and biographies — so reach for it over "was going to" when the tone is official. Negative: was / were not to.
The ceremony was to be held at Haffenbridge School.
This discovery was to become one of the most important of the century.
The delegates were to meet again the following spring.
Not "The official report says the ceremony was going to be held at noon." — say "The official report says the ceremony was to be held at noon.". In a formal report, an arrangement takes was to; "was going to" sounds too casual for that register.
Try it: A formal report reads: The treaty ___ reshape the region for a century. (was to / is to / will to) Answer: was to — Seen from the past, a formal arrangement or destiny takes was to + the base verb: was to reshape. "Is to" is the present version, but the report looks back. "Will to" is not a real form.
was / were about to + verb (right on the brink)
For something on the very brink of happening at a past moment, use was / were about to + the base verb: "She was about to sign when the lawyer stopped her." What it adds is imminence — not a plan you held for weeks, but the next instant. That is why it so often sits with a when-clause that interrupts it, and why swapping in was going to loses the sense of the brink and leaves an ordinary intention. A close relative is was / were supposed to, which names an expectation or obligation someone placed on you — "The report was supposed to be finished by Friday" implies someone is answerable for the fact that it was not. Both are everyday register; neither belongs in the formal report language of was to.
She was on the point of signing. — She was about to sign when the lawyer stopped her.
Their plan was to leave at dawn, and the obligation was someone else's. — They were supposed to leave at dawn.
The engine started just before we gave up. — We were about to give up when the engine started.
Try it: Diego ___ press send when he noticed the attachment was missing. (was about to / was due to / was to) Answer: was about to — Noticing something mid-action puts him on the very brink, which is 'was about to'. 'Was due to' would point at a scheduled slot on a timetable, but no time is given here. 'Was to' marks a formal arrangement in report register, which is far too ceremonious for someone hitting send on an email.
The would have that is NOT looking ahead
One form needs separating from the rest, because it wears the same clothes. You have met would have + the past participle as a look-ahead that was already complete by a later past point: "By the time she arrived, the ceremony would have ended." But the same words also carry a completely different job — the unreal one: "a conference he otherwise would never have attended" says he DID attend, and describes only what would have happened in a world that did not occur. The giveaway is a word like otherwise, but for that, or an if-clause nearby; those mark a condition that was never met. So the test is to ask whether the event the would have describes really took place: if it did, you are looking ahead from the past; if it did not, the sentence is unreal.
By the time she arrived, the ceremony would have ended. (look-ahead: it did end)
He met Amina at a conference he otherwise would never have attended. (unreal: he DID attend)
Without the delay, they would have missed each other entirely. (unreal: they did not miss each other)
Try it: Which sentence uses 'would have' for something that did NOT happen? (But for the storm, the climbers would have reached the summit that afternoon. / She knew that by nightfall the search party would have turned back, and they reached camp at dusk. / By the time the inspector called, the crew would have cleared the site, and indeed it stood empty.) Answer: But for the storm, the climbers would have reached the summit that afternoon. — 'But for the storm' names a condition that was never met, so reaching the summit is the unreal outcome — they did not reach it. The other two look ahead from a past moment to something the sentence then confirms: the party reached camp at dusk, and the site did stand empty. Ask whether the event took place; if it did, the 'would have' is a look-ahead.
Which form? A quick map
Five forms look forward from a past moment — you pick by flavor, plainest to most formal. (1) would is the neutral default: from then, this still lay ahead ("she knew it would end"). (2) was going to adds a personal plan or intention, often one that fell through ("I was going to call, but ..."). (3) was about to puts you on the very brink, the next instant rather than the next month ("he was about to sign when ..."). (4) was due to points at a scheduled time on a timetable or calendar ("the train was due to leave at nine"). (5) was to marks a formal arrangement or an appointed fate, in report-and-history register ("she was to become queen"). Quick test: plain look-ahead → would; my own plan → was going to; the very next moment → was about to; a fixed clock time → was due to; an official arrangement → was to. One caution: would have + the past participle is on this map only when the thing really happened; when a word like otherwise or an if-clause is nearby, it is the unreal use instead.
He sensed the storm would pass by morning.
We were going to repaint the hall, but ran out of time.
The coach was due to leave at nine sharp.
By royal decree, she was to open the new library that spring.
Not "The timetable said nine, so the coach was going to leave at nine." — say "The timetable said nine, so the coach was due to leave at nine.". A time fixed by a timetable is was due to; was going to would make it the coach's own plan.
Try it: A palace record notes that, by the decree of that year, the young prince ___ be crowned on the first day of spring. (was to / was going to / was due to / would) Answer: was to — A decree laying down what has to happen is an official, appointed arrangement, which is the report-register was to be crowned. "Was going to" would make it the prince's own plan rather than a ruling; "was due to" treats it as a timetable slot rather than a requirement; "would" is the plain narrative look-ahead and says nothing about the decree that fixed it.