Loop posts only show with Recent Posts widget

Pretty sure I’m missing something obvious, but I have a basic loop that calls the last post, then pulls the title, thumbnail, and content. It works fine with the default Recent Posts widget in the sidebar, but when I remove it, the content is empty (but thumb and title still show up fine).

<div id="latest-post">
<?php if (have_posts()) : ?>
<?php while (have_posts()) : query_posts('p=1'); ?>
<h1><?php  the_title(); ?></h1>
<?php echo get_the_post_thumbnail(); ?>
<?php the_content('Read on »') ?>
<?php endwhile; ?>
<?php endif; ?>
</div><!-- #latest-post -->

It’s not a huge deal, I can live with the recent posts widgets, but I’m just wondering what I’m missing, and I couldn’t find anything on it.