Calbayog began as early as 1600 in a settlement called Hibatang by the river bank of the present Oquendo River. It had 2,000 inhabitants under the spiritual guidance of a certain Jesuit, Father Ignacio de Alzina.

The present barangay Anislag was the forerunner of Calbayog settlement. The barangay is located along the river bank of Oquendo river, about ten kilometers north off the city proper. Historical remains of what was once a village church can be noticed by travelers passing this barangay.

The place was often visited by flood during stormy days, so Anislag settlement became unsafe. The hardy settlers left the place in “balotos” (bancas) and hastily rigged bamboo raffs following the river towards the sea. At Cahumpan (now barangay Cahumpan) they decided to stop just for a moment’s break. Somehow, at the spur of the moment and by common consent, they settled down at Cahumpan to start life anew.

More settlers came. Some crossed the river to Sabang (now barangay Trinidad). After a certain period of time, the restless settlers moved again and settled at Taboc (now barangay Obrero), a settlement which directly face the open Samar sea. The place was once a vast swampland which extended from the present Nijaga Park, where the monument of national hero Dr. Jose P. Rizal and local hero Benedicto P. Nijaga now stand.

Taboc is the place where the name Calbayog began. Taboc, so legend says, once abounded with “Bayog” trees. They were cut down and burned for fuel in making “Cal” (lime) out of sea shells and corals. From these two things, the Spaniards called the place “Calbayog”. The second version says that there was once a man named “Bayog”. It so happened that there was no other path leading to the sea except at Bayog’s place. Fishermen used to say “tikang kami kan Bayog” (we came from Bayog) or “makadto kami kan Bayog” (we shall go to Bayog).

One day a “guardia civil” asked for the name of the place. The fisherman mistaking the query for another thing, answered “tikang kami kan Bayog” (we came from Bayog), with the correct query and a wrong answer, the Spaniard took the last words, “kan Bayog”, for the name of the settlement. A lot of tongue-twisting and mispronunciation changed the original name of Calbayog.

Republic Act No. 328 made Calbayog a city on October 16, 1948. In 1961 R.A. 328 was repealed by R.A. 3879, an act which revised the City Charter.