When he had finished his studies, he stayed in Saint Petersburg, having a daytime job in a factory and pursuing his artistic interests in his free time.

At the outbreak of World War I, Rūdolfs Pērle was sent as an expert on military observation balloons by his employer, who manufactured them, to the front in the Caucasus.

[1] Encountering the wild and mountainous landscape and the destruction brought by the war provided strong inspiration for Pērle, who in the last years of his life thus came to adopt new and darker themes and modes of expression.

Until then, his oeuvre mostly consisted of still lifes of flowers, but following his impressions during the war, he began an intense production of oneiric, expressive landscapes, characterised by an atmosphere of desolation.

[1] He has been compared to his contemporary Lithuanian artist colleague Mikalojus Konstantinas Čiurlionis and described as an important representative of Symbolism within Latvian art.