How come I can't move the contents of my .htaccess file into my virtual host?

According to the docs, RewriteBase "Sets the base URL for per-directory rewrites".

Since you're not setting up per-directory rewrites, the directive is meaningless outside of an .htaccess file for a particular directory.

RewriteBase does not work in virtualhost files.

The question you probably want to ask is:

How do I include relative paths in VHost RewriteRules?

Particularly, in vhosts, *_FILENAME returns a slash followed by the REQUEST_URI, instead of being relative or mapped to the filesystem!
Eg, %{SCRIPT_FILENAME}

• In .htaccess: "assets/style.css"
• In a vhost file: "/assets/style.css"
• You need: "/var/www/assets/style.css"

There are several solutions:

• Solution #1: %{DOCUMENT_ROOT}

  RewriteRule ^/foo/bar$ %{DOCUMENT_ROOT}/foo/bazRewriteCond %{DOCUMENT_ROOT}/%{SCRIPT_FILENAME} !-fRewriteRule (.*) /script.cgi

• Solution #2: <Directory> tags

  RewriteEngine On<Directory "/var/www/">    ...    RewriteCond %{SCRIPT_FILENAME} !-f    RewriteRule (.*) /script.cgi</Directory>

  Within the directory tag, *_FILENAME is treated the same as in a htaccess file.
  There may be an issue using this when the server has multiple aliases.

• Solution #3: %{REQUEST_URI}

  Use %{_URI} instead of %{_FILENAME} where possible
  Not a real answer. Just pointing out that *_URI's won't have to be rewritten as they are not supposed to map to the filesystem, and therefore vhost/htaccess paths are the same. However, it is not always possible to use REQUEST_URI, and David Faux commented above that it is slower. Besides, thi