Joining multiple post queries

How can I join together two post queries in my Archives template? I am trying to create a custom sort order for which I need one query’s posts first, followed by another. I tried this but doesn’t work:

global $query_string;
$posts1 = get_posts($query_string . “&p=1”);
$posts1 = get_posts($query_string . “&p=2”);
$post = array_merge($posts1, $posts2);

(query parameters obviously simplified)