$  During the first half of the thirties Polish bomber air force was equipped with old Breguer XIX and       $
$Potez XXV aircrafts. Since 1935 the existing aircrafts were gradually replaced by newly designed PLZ Karas  $
$(Kara)  aircrafts. Karas bombers were a part of 12 front-line squadrons. At the moment of starting the     $
$Second World War the construction of PZL 23 aircraft was already obsolete. Unfortunately it was not possible$
$to start the serial production of PLZ 45 Sum, the follower of Karas.  For this reason Karas aircrafts had to$
$participate in the September war operations. Five squadrons were part of the Bomber Brigade, left at the    $
$disposition of the Commander-in-Chief. The remaining seven flights were distributed among army air forces   $
$and used primarily for reconnaissance flights. In 1938 the air force was joined by a new type of aircraft,  $
$which in accordance of the military wording was considered a medium-size bomber. PLZ Los (o) aircraft had $
$very good characteristics, which were as good or even better than the parameters of similar constructions   $
$used by Luftwaffe.  Los aircrafts became part of 4 bomber squadrons of the Bomber Brigade.  The two         $
$remaining squadrons served as equipment supply. In the Defence War Los aircrafts participated contrary to   $
$their destination. The aircrafts, destined for long-distance bombing flights of industrial sites and fuel   $
$storage sites were made to participate in storming air raids at enemy's armour troops. Moreover the storming$
$missions took place without any fighter coverage, and in consequence this valuable equipment was quickly    $
$destroyed as a result of enemy air fighter operations of and air defence. At the same time the              $
$self-sacrifice of Bomber Brigade pilots effectively delayed the march of XVI Armoured Corps which after     $
$having broken through Polish defence line near Czestochowa was approaching  Warsaw. During the second stage $
$all undamaged bombers were first evacuated East, and then to Romania. Los aircrafts taken over by Romanians $
$were used in fights against the Red Army during the Barbarossa Operation.                                   $
