Build timelines with AI

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Please build a timeline for Chronlines (https://chronlines.com), an app that draws events as a zoomable timeline.

Topic: (describe your timeline here)
Number of events: about 40

Reply with only the timeline as CSV in a single ```csv code block, in the format below, so I can paste it straight into Chronlines. No other text before or after the code block.

## Chronlines import format (CSV)

The first line is this header, exactly:

title,date,end_date,tier,tags,description,source_url

One event per line after that. Columns:

- title (required): short event name, at most 200 characters.
- date (required): when it happened or began. See "Dates" below.
- end_date (optional): when it ended, for events that span time (a war, a reign, a life). Leave empty for single moments.
- tier (optional, default 1): importance. 1 = always shown (the key events, roughly 1 in 5); 2 = shown when the reader zooms in; 3 = fine detail shown when zoomed in further.
- tags (optional): up to 20 short labels separated by semicolons, e.g. war;politics. Reuse a small set of tags across the timeline so readers can filter by them.
- description (optional): one or two plain sentences, at most 2000 characters. No Markdown.
- source_url (optional): one http(s) link to a reliable source for the event. Only include a URL you are confident exists; otherwise leave it empty.

CSV rules: separate fields with commas. Wrap a field in double quotes if it contains a comma, a double quote or a line break, and write a double quote inside a quoted field as "". Leave optional fields empty rather than writing "none" or "n/a". At most 5,000 events per import.

### Dates

Prefer ISO forms, as precise as the facts allow and no more:
- Day: 1969-07-20   Month: 1969-07   Year: 1969
- Before the common era: 44 BCE, 500 BCE, 66000000 BCE (never a bare negative number like -500)
- Approximate: c. 1450   Uncertain: 1450?
- Decade: 1960s   Century: 20th century, 5th century BCE   Season: spring 1969
- Ongoing or open-ended: leave end_date empty.
Times of day are not supported. A bare year means the whole year, not January 1, so don't invent a month or day you don't know.

## Quality

- Be accurate. Use well-established dates; if historians disagree, use "c." and say so in the description.
- Cover the whole span of the topic, not just the famous moments, and put events in chronological order.
- Use end_date for things that last (lives, reigns, wars, eras) so they draw as spans.
- Don't repeat an event, and don't add filler events to reach a number.
- Write neutral, factual descriptions in your own words.

## Example

```csv
title,date,end_date,tier,tags,description,source_url
Apollo program,1961-05-25,1972-12-19,1,program,"NASA's crewed Moon program, from Kennedy's address to Congress to Apollo 17.",https://www.nasa.gov/the-apollo-program/
Apollo 11 Moon landing,1969-07-20,,1,mission;landing,Neil Armstrong and Buzz Aldrin become the first people to walk on the Moon.,
Apollo 13,1970-04-11,1970-04-17,2,mission,"An oxygen tank explodes on the way to the Moon; the crew returns safely.",
Plans for a crewed Mars mission,2030s,,3,future,"NASA's long-range goal, still tentative (""Moon to Mars"").",
```