When the war ended he remained in the German Army, serving with the First Engineer Battalion in Munich, becoming adjutant in mid 1919.

After returning to Germany, in May 1932 Ibel was promoted to Hauptmann, and served as an Instructor with the flight school (Jagdfliegerschule) in Schleissheim.

On 1 April 1936, I. Gruppe (1st group) of Jagdgeschwader 232 (JG 232—232nd Fighter Wing) a newly formed in Bernburg and placed under the command of Major Bruno Loerzer.

[2] On 15 March 1937, Ibel was transferred and tasked with the creation of I. Gruppe of Jagdgeschwader 135 (JG 135—135th Fighter Wing) at Bad Aibling, becoming the first Gruppenkommandeur (group commander).

During the Anschluss in March 1938, (the unification between Germany and Austria) the Gruppe was briefly moved to Hörsching Airfield near Linz before reurning to Bad Aibling on 30 April.

On 26 August, JG 3 was ordered to relocate to Brandis near Leipzig, and tasked with protecting the central German industrial area.

[4] World War II in Europe began less than a week later on Friday 1 September when German forces invaded Poland.

The objective of this operation was to give the German battleships Scharnhorst and Gneisenau and the heavy cruiser Prinz Eugen fighter protection in the breakout from Brest to Germany.

In support of this, the Luftwaffe, formulated an air superiority plan dubbed Operation Donnerkeil for the protection of the three German capital ships.