Captive observation balloon on a towing vessel to monitor the French coast against submarines in 1917. Photograph published by the French weekly<i> The Mirror</i>, December 2, 1917.
Unknown author<span style="display: none;">Unknown author</span>
1917-12-02
<i>Le Miroir</i> December 2, 1917, page 12 (via <a rel="nofollow" class="external text" href="http://gallica.bnf.fr/ark:/12148/cb40360453x/date1917">Gallica.fr</a>)