Stich was born in Rogahlen in East Prussia, now named Rogale and located in Poland.
He was the son of a salesman, also named Wilhelm Stich, and his wife Wilhelmine Dublaski.
[1] Stich joined the Nazi Party in 1925 (membership number 18,327) shortly after the lifting of the ban that had been imposed on it in the wake of the Beer Hall Putsch of November 1923.
On 6 December 1925, Gau East Prussia was officially established and Stich became its first Gauleiter.
[2] By early 1926, Stich had been ousted from his Gauleiter position due to his inability to solve the financial problems of the Gau.