The "merge" command:

Usage: fossil merge ?OPTIONS? ?VERSION?

The argument VERSION is a version that should be merged into the
current checkout.  All changes from VERSION back to the nearest
common ancestor are merged.  Except, if either of the --cherrypick or
--backout options are used only the changes associated with the
single check-in VERSION are merged.  The --backout option causes
the changes associated with VERSION to be removed from the current
checkout rather than added.

If the VERSION argument is omitted, then Fossil attempts to find
a recent fork on the current branch to merge.

Only file content is merged.  The result continues to use the
file and directory names from the current checkout even if those
names might have been changed in the branch being merged in.

Other options:

  --baseline BASELINE     Use BASELINE as the "pivot" of the merge instead
                          of the nearest common ancestor.  This allows
                          a sequence of changes in a branch to be merged
                          without having to merge the entire branch.

  --binary GLOBPATTERN    Treat files that match GLOBPATTERN as binary
                          and do not try to merge parallel changes.  This
                          option overrides the "binary-glob" setting.

  --case-sensitive BOOL   Override the case-sensitive setting.  If false,
                          files whose names differ only in case are taken
                          to be the same file.

  -f|--force              Force the merge even if it would be a no-op.

  --force-missing         Force the merge even if there is missing content.

  --integrate             Merged branch will be closed when committing.

  -n|--dry-run            If given, display instead of run actions

  -v|--verbose            Show additional details of the merge