Finnish Air Force fin flash from the 18th of March 1918.
<p>On the 18th of march 1918 CIC of the Army general baron Carl Gustaf Emil Mannerheim issued an order Nr. 26 officially approving first Finnish Air force aircraft insignia.
</p><p><i>All troops are now informed that our aircraft will use from now on as a recognition mark the following sign (swastika) in blue colour on the wings and fuselage, in addition a red flag with a yellow cross will be attached to the tail.</i> 
</p><p>The flag is known to have been applied on only two planes (F2 and F3). 
</p>
Keskinen, K., Stenman, K. &amp; Niska, K. (1996) <i>Suomen ilmavoimien maalaukset ja merkinnat / Finnish Air Force camouflage and markings</i>. Tampere: Apali (<a href="//commons.wikimedia.org/wiki/Special:BookSources/9525026051" title="Special:BookSources/9525026051">ISBN 9525026051</a>)
<a href="//commons.wikimedia.org/w/index.php?title=User:Flagicon&amp;action=edit&amp;redlink=1" class="new" title="User:Flagicon (page does not exist)">Flagicon</a>
1918-03-18
<span class="int-own-work" lang="en">Own work</span> <a rel="nofollow" class="external text" href="http://www.puolustusvoimat.fi/wcm/4b7254804a2c633895aa9f72e6383058/2/Albatros_440.jpg?MOD=AJPERES&amp;CACHEID=4b7254804a2c633895aa9f72e6383058/2">Sample of use on Albatros B.II</a>