For centuries they had separate feasts, until they were finally united in the most recent liturgical calendar.
Sts. Joachim and Anne are regarded as Jesus’ grandparents, being the parents of the Virgin Mary.
Little is known about their lives, as they are not mentioned in scripture.
However, the Church has venerated them as saints since the early years, and gave various dates in the calendar to them.
According to the Catholic Encyclopedia, St. Joachim had a number of dates throughout history.
St. Joachim was honored very early by the Greeks, who celebrate his feast on the day following the Blessed Virgin’s birthday [September 9]; the Latins were slow to admit it to their calendar, where it found place sometimes on 16 Sept. and sometimes on 9 Dec. Assigned by Julius II to 20 March, the solemnity was suppressed some fifty years later, restored by Gregory XV (1622), fixed by Clement XII (1738) on the Sunday after the Assumption, and finally raised to the rank of double of the second class by Leo XIII (1 Aug., 1879).
St. Anne had fewer dates on the calendar, including July 26, the day it is celebrated today.
Her feast is celebrated in the East on the 25th day of July, which may be the day of the dedication of her first church at Constantinople or the anniversary of the arrival of her supposed relics in Constantinople (710) … Her feast, under the influence of the “Golden Legend,” is first found (26 July) in the thirteenth century,
While the new liturgical calendar combines their feasts on July 26, the Eastern Church has also celebrated their memory on a single day.
The Greeks keep a collective feast of St. Joachim and St. Anne on the 9th of September.
This feast is known as the Synaxis of Sts. Joachim and Anne, maintaining their connection to Mary, whose birthday is celebrated on September 8.
Pope Francis has now used this feast of July 26 to celebrate grandparents and their contribution to society.