After just checking the second Robservation's slidsehow, I suddenly realized what an important day February 20th was every year that DS was on
1967: Ep #171 - The aftermath of Dr. Guthrie's seance in which Josette spoke through Vicki and issued a warning.
1968: Ep #432 - Abigail discovered Barnabas, he forced her to face the truth, she died of a heart attack.
1969: Ep #694 - Quentin's Ghost drove the family from Collinwood and laughed hysterically when he had the house to himself.
1970: Ep #955 - After learning the truth about Nicholas and her husband Sky, Angelique was reunited with Barnabas, but when he spuned her and she discovered his relationship with Maggie, she cast a spell so that Maggie and Quentin thought they were in love.