This is the first evidence that we have gathered that demonstrates that he was in the German Army. We know that brothers Karl, Moritz, and Theo were in the German military, and we also know that Julius' older brother Jakob was in the United Sates Army.
This postcard from Julius to his sister Anna in Brooklyn, New York does not say much, but it does tell us that he indeed was in the army, and that Anna was sending him money, like she did her other relatives who remained in Germany.
Below is the postcard that he sent to Anna, followed by the English translation.
With thanks to Matthias Steinke for providing this translation to English, below is that translation:
14 February 1915
Dear sister Anna!
Receive many thanks for the sent money. I am now at the Baltic-coast.
Otherwise, I am fairly fine. If I have more time, I will write more. Many greetings to all. Again many thanks.
Many greetings from your Julius
My address: Private Braunhart
1st Reserve Replacement Battalion (of the) Infantry - Regiment 9
3rd company Danzig-Heubude