In the British Isles, Midsummer Eve, the evening before the Christian Feast of St John the Baptist, was celebrated on 24th of June. Old Midsummer's Eve fell on a later date (one which Americans will certainly recognize), after the calendar change of 1752. In the old Julian calendar, June 24th was celebrated as the Summer Solstice and the counterpart to the December 25th Winter Solstice.

This calendar change has to do with Pope Gregory XIII (1572-1585), who changed the scope of the Julian calendar. During the sixteenth century, the calendar was ten days slow, as the Romans’ during the reign of Julius Caesar was ten days behind the sun. Under Pope Gregory’s orders, a more accurate calendar was constructed and the Julian calendar was replaced with the Gregorian calendar. The correction of the drifting of the calendar away from the astronomically fixed moments of the solstices and equinoxes was the very reason for the Gregorian reform (so that the date of Easter could be reliably calculated by the Church). Ten days were “skipped” in October of 1582 to realign the calendar correctly with the sun.

However, many non-Catholic countries did not go along with this calendric change for years, so England did not adopt the modern Gregorian calendar until 1752 (one hundred and seventy years later). With the old Julian calendar eleven days behind the new Gregorian calendar, it was necessary to drop the eleven days. In the 1752 reform in Britain, the old Julian calendar was eleven days off, which required the change made wherein the 11:59 PM September 2, 1752 was followed by 12:00 AM September 14, 1752.

This was how the people of Europe came to celebrate Old Midsummer’s Eve on July 4th (eleven days after June 23). Many people found it hard to accept that eleven days had just disappeared, so they continued to refer to holidays by the old Julian calendar by the word “old” before the holiday. The “new” date of July 4th was actually the “old” June 23rd. As a result, instead of celebrating Midsummer’s Eve on June 23th, many celebrated Old Midsummer’s Eve on July 4th.

Thus, in Europe, the Feast of St John, commonly known as Midsummer Day, occupied much the same relationship with the solar cycle as Christmas Day; it represented the end of a solstice, the period in which the sun ceased to move for a short period, but rose and set at the same points on the horizon at the extreme end of its range. Now, however, the sun was at the height of its strength, and light at its longest, and Midsummer Eve represented the culmination of that period of apogee, just before the days began to shorten again as the sun moved southward. Thus Midsummer was a time of both increase and decrease of the sun’s power.

According to the Christian liturgical calendar, the Nativity of St John the Baptist on June 24th comes three months after the celebration on March 25th of the Annunciation, when the Archangel Gabriel told Mother Mary that her cousin Elizabeth was in her sixth month of pregnancy, and six months before the Christmas celebration of the birth of Jesus. The purpose of these festivals, like the pagan ones before them, was not to celebrate the exact dates of these events, but simply to commemorate them in an interlinking way. Thus, the Nativity of St. John the Baptist anticipates the feast of Christmas. (In Eastern Christianity also, the Feast of his Nativity is celebrated on June 24th.) All over Europe, St John's Day festivities are closely associated with the ancient nature lore of the great summer festival of pre-Christian times. Just as the ancient pagans celebrated their first day of summer festival, “Beltane” (on the eve of May 1st), with mountaintop or hilltop bonfires, “Saint John's fires" were lighted on mountains and hilltops on the eve of his feast. As the first day of summer, St John's Day is considered in ancient folklore one of the great "charmed" festivals of the year.

The question naturally arises as to why the celebration falls on June 24th rather than June 25th, if the date is to be precisely six months before Christmas. It has often been claimed that the Church authorities wanted to Christianize the pagan solstice celebrations and for this reason advanced St John's feast as a substitute. However, it has been objected that this is a questionable claim regarding the Summer Solstice, because in the Middle Ages the solstice took place around the middle of June due to the inaccuracy of the Julian calendar. It is stressed that it was only in 1582, through the Gregorian calendar reform, that the solstice returned to June 21st as it had been in the fourth century, with the Julian dating. Therefore, it is argued that a more likely reason why the festival falls on June 24th lies in the Roman way of counting, which proceeded backward from the Kalends (first day) of the succeeding month. Christmas was "the eighth day before the Kalends of January" (Octavo Kalendas Januarii). Consequently, it is argued, that St John's Nativity was put on the "eighth day before the Kalends of July." But, since June has only thirty days, in our present (Germanic) way of counting, the feast falls on June 24th.

However, even though this explanation is a perfectly reasonable one to account for the discrepancy between the June 24th and June 25th dating of the Feast of St John, it is not entirely convincing, since we’re (a) still taking about early Roman Christian dating and (b) looking only at a three day difference in dating from June 21st to June 23rd—still around the time of the Summer Solstice. The Feast of St John the Baptist dates to the time of Christianity making its inroads into Gaul (France). As was the custom of the early Church, local customs and feasts were assimilated into church-life and its liturgical year. Celts, Romans and Franks lit bonfires (feux de joie, or “fires of joy”) in honor of the full power of the sun at Summer Solstice, fire being associated with the origin of life through the sun. (In the seventh century, Saint Eligius warned against midsummer activities and encouraged new converts to avoid them in favor of the celebration of St John the Baptist’s birth.) By declaring the solstice to coincide with St. Jean-Baptiste Day, the common people simply continued age-old traditions but for a different purpose. Thus, in the Christian adaptation, the fires have since become the focal point of the festivities, for they represent the “Light of the World”—Christ (the sun/son of God)—whom John the Baptist came to announce.

While it is argued that we cannot see (because of the change from the Julian to the Gregorian calendars) an outright Christian co-optation of the ancient pagan Summer Solstice celebration in the Feast of St John the Baptist, it is nevertheless extremely significant in terms of the universal pre-Christian mythology of the sun (and its symbolism; e.g., the burning sun-wheels of the pagan Midsummer bonfire festival) and sun-gods. There is an essential solar component in these Midsummer rites, which celebrate the sun at its full power (before it begins its decrease).

Sir James Frazer, in his The Golden Bough, suggested that their point in the calendar indicated that they were ceremonies of a surviving ancient sun-worship, and later emphasized them as rites of protection and blessing. Therefore, the Feast of St John the Baptist (on June 24th) falling around the time of the Summer Solstice is considered by many to be significant, recalling the words of John the Baptist with regard to Jesus: "He must increase, but I must decrease" (John 3:30). This statement, considered in its metaphorical sense, reminds of the old pagan contest of the Oak King and Holly King. In pagan folklore, the Oak King is seen as the ruler of the year between Winter Solstice and Summer Solstice, and the Holly King from summer to winter. At each solstice they vie for power, and while the Oak King may be in charge of things at the beginning of June, by the end of Midsummer he is defeated by the Holly King, who brings in the Winter Solstice (the seasonal cycle of increase and decrease).

To come full circle from the beginning of this Midsummer Eve dating exposition, considering that Americans are about to celebrate the birthday of the country, when The Declaration of Independence, approved on July 4, 1776, a little-known fact: July 4th was once known as "Old Midsummer Eve" or "Little St. John's Day" in parts of England. (Again, owing to the calendar changes of 1752, the date of Midsummer was moved.)