Wordpress apache2 virtual host configuration on a debian install
Do you notice the <VirtualHost *:80> in your murmillosoftware.com.conf file? That is called the Virtual Host configuration. In your current blog.murmillosoftware.com.conf, all you're doing is creating an alias to /wp path, which is why you're able to browse wordpress there.
Update your blog.murmillosoftware.com.conf as follows (might be buggy, keep checking server logs):
<VirtualHost *:80> ServerAdmin erik@murmillosoftware.com ServerName blog.murmillosoftware.com DocumentRoot /usr/share/wordpress # Custom log files, to differentiate from root server ErrorLog ${APACHE_LOG_DIR}/error-wordpress.log CustomLog ${APACHE_LOG_DIR}/access-wordpress.log combined Alias /wp-content /var/lib/wordpress/wp-content <Directory /usr/share/wordpress> Options FollowSymLinks AllowOverride Limit Options FileInfo DirectoryIndex index.php Require all granted </Directory> <Directory /var/lib/wordpress/wp-content> Options FollowSymLinks Require all granted </Directory></VirtualHost>