How to display posts with a certain tag

I originally asked this question over at stackoverflow with no luck so far so I will cross post it to here if that is okay.

I have found that I cannot seem to be able to locate the posts and I'm thinking I will need to use a custom wp_query loop to locate them but I'm not to sure.

The question.

I'm really struggling at what I am sure is a simple problem. I cannot seem to get the posts which fall under a certain tag to display on that tags page ie: (/tag/blog/) with blog being the Tag.

So far following the Official Tag Templates page on Wordpress I still cannot seem to get it working.

I do not need a heirarchy so tag.php works fine. Using single_tag_title() it does correctly display the tag at the top of the page.

The rest of the Official Tag Templates does not really give much more detail on wether or not I can use the default Loop or a custom one. I have tried with the custom one as shown below but that does not work. (I've kept it down to the minimum not currently worried about styling.)

<?php get_header(); ?>
<p>Tag: <?php single_tag_title(); ?></p>
<div class="container">
    <div id="content" class="clearfix row">
        <div id="main" class="col col-lg-8 clearfix blog-page-padding" role="main">
            <?php 
                if ( have_posts() ) :
                    while ( have_posts() ) :
                        the_title();
                    endwhile; // end while
                endif; // end if
            ?>
        </div> <!-- end #main -->
    <?php get_sidebar('blog'); // Blog ?>
    </div> <!-- end #content -->
</div>
<?php get_footer(); ?>

So this code currently does display the title of the Tag but not the title of the posts which I am trying to get out.

To wrap the question up. "How do I display the posts which fall under a certain tag."