The back makes reference to the timeframe of 24 December, 1914 - 8 April, 1915. A mention of a location in France is made, then ends with the date 19 March, 1915.

When researching the meaning of "1915 Parole Weimar" (Parole can be translated as "slogan" or "password") the only source I found comes from an article in 'Das Reichsbanner', newspaper of the organization 'Reichsbanner Schwarz-Rot-Gold'. The article regards a Youth Leader Training Course that took place from September 18 to 20, 1931. The excerpt that mentions it is transcribed here, by Gemini AI as there were errors in the text copied from the PDF, which is also linked here. If you are able to make or aquire a better translation, please do edit this one.

https://www.reichsbanner-geschichte.de/media_zeitungen/media_zeitung/1931-10-24/1931-10-24_Chemnitz-Westsachsen-Zwickau-Ostsachsen-Dresden.pdf

-------------
"The youth leaders of this course vowed to do everything they could to march in Weimar in great strength and with tents. On Saturday, six comrades made themselves available to peel potatoes. Even Comrade "Schweit" was not missing, because there was a farewell dinner on Sunday: potatoes, red cabbage and goulash. Everyone dug in heartily. Several comrades already had to leave in the morning in order to arrive back in their hometowns before midnight. Our parting greeting was "Slogan Weimar." We from Chemnitz did not depart from Neukirch-Ost until 3:10 PM and had a layover in Dresden. We visited the Volkshaus [Labor/Community Union House], where we also thought of our comrade Schümann. We rang the bell several times, but Reinhold was not home; perhaps it will work out another time. In Chemnitz, we said goodbye to each other with a "Frei Heil!" [Free and Well! / Hail Freedom!].

"We cherish the memory of the time we spent on the Valtenberg and give many thanks to our hut warden, Licholt, for the hospitality he showed us. Upon our departure from the Valtenberg, he had also hoisted our beautiful black, red, and gold flag. We from Chemnitz also thank our comrades Nehls and Harrens for their self-sacrificing work, which they performed for our good cause; hopefully, it has fallen on fertile soil. To all course participants, I, as the eldest, call out to you: apply what you have learned in your local groups and do not let up until we, as the youth, are even more solid and stronger than we are now. Therefore, comrades, prepare for the 1932 National Rally, "Slogan Weimar."

"Greetings to you all from your comrade Schweit."
-------------