How can one change the timestamp of an old commit in Git?

Question

The answers to How to modify existing, unpushed commits? describe a way to amend previous commit messages that haven\'t yet been pushed upstream. The new messages inherit t

Answer 1

How to Edit Multiple Commit Dates

Other answers aren't very convenient for editing several commit dates. I've come back to this question after a few years to share a technique.

To change the dates of the last 4 commits:

git rebase -i HEAD~4

Edit the rebase as follows, inserting exec lines to modify dates as needed:

pick 4ca564e Do something
exec git commit --amend --no-edit --date "1 Oct 2019 12:00:00 PDT"
pick 1670583 Add another thing
exec git commit --amend --no-edit --date "2 Oct 2019 12:00:00 PDT"
pick b54021c Add some tests
exec git commit --amend --no-edit --date "3 Oct 2019 12:00:00 PDT"
pick e8f6653 Fix the broken thing
exec git commit --amend --no-edit --date "4 Oct 2019 12:00:00 PDT"