Petar Angelov was born in 1878 in Haskovo, in today’s Bulgaria, then part of the Ottoman Empire. After he finished a military academy he served as a sergeant in the 24-th infantry regiment. In 1900 he joined the revolutionary organization IMARO, and in 1903 he became a military instructor in the revolutionary band of Mihail Gerdzhikov in Odrin Thrace.
After the end of the uprising, he went back to Bulgaria and from June 14, 1904, he became a leader in the region of Kriva Palanka. His revolutionary band had 25 members: 14 freedom fighters were born in the liberated parts of Bulgaria, Rudolf Goliyat came from Austria and Anton Hoshek was a Czech. On January 2, 1905, he participated at the Congress of Skopje in the village of Knezhevo.
At the second Congress of the Skopje Revolutionary Region during November 1906, he became an illegal member of the Skopje regional revolutionary committee.