Today's calendar piles it on: a medieval tsar getting a hard lesson outside Plovdiv, sixteen name-day variants that all trace back to the word for Sunday, and a Rhodope town throwing its annual feast. Pour the coffee; this one has range.

What happened on this day

First, the setting. After the Fourth Crusade seized Constantinople in 1204 and set up the Latin Empire on Byzantine soil, Bulgaria's Tsar Kaloyan handed the newcomers one of the great shocks of the age: his army annihilated the Crusaders at Adrianople in 1205, and Emperor Baldwin himself died a prisoner in Tarnovo. Then in 1207 Kaloyan was murdered while besieging Thessalonica, in a conspiracy organised by his own cousin Boril, who took the crown while the legitimate heir, the boy Ivan Asen II, still had supporters but no throne. Medieval Bulgarian succession was not a gentle business.

On 30 June 1208 by the Julian calendar then in use, which lands on 7 July in the modern reckoning, Boril met the main Latin army outside Philippopolis, today's Plovdiv. On paper he was well set: between 27,000 and 30,000 men, including some 7,000 Cuman horse-archers of the kind that had shredded the knights at Adrianople. Boril ran the same playbook, harassing cavalry stretching the Crusader line towards a waiting trap. The knights, however, remembered Adrianople perfectly well, declined the bait, and sprang a trap of their own on the detachment the tsar was personally commanding, a mere 1,600 men. Boril fled, and the whole Bulgarian army pulled back. Copying a genius's exam answers, it turns out, works less well when the examiner has read them too.

The retreat was the redeeming feature. The Bulgarians withdrew towards the Turia pass, knowing the Crusaders would not follow them deep into the mountains, and near the village of Zelenikovo the rear guard turned and mauled its pursuers until the main army had passed through safely. The Crusaders fell back to Philippopolis. The defeat stung but it was not a catastrophe: the war resumed the following year, the Latin Emperor Henry talked Alexius Slav, lord of the Rhodopes, into switching sides and marrying his daughter, and peace eventually arrived the way medieval peace usually did, with a wedding, when Kaloyan's daughter Maria of Bulgaria married Henry himself.

Today's name days

7 July is St Nedelya's day, and it comes with one of the loveliest quirks in the Bulgarian calendar: неделя is the word for Sunday, from the old Slavic for a day of no work, so Bulgaria spends today congratulating people who are, quite literally, named Sunday. The saint behind it is the early Christian martyr known in Greek as Kyriaki, "of the Lord's day", whom Bulgarian tradition renders as Sveta Nedelya; Sofia's landmark St Nedelya Church carries her name. Language collectors may also enjoy that the same word means "week" in Russian, which has confused generations of learners in both directions.

Nedelya itself, and the paired forms Nedyalko and Nedyalka, lead the day; the poet Nedyalko Yordanov is one of the best-known modern bearers of the male form.

Then there is the Delyo family of names, Delyan, Delyo, Delcho, which carries my favourite fact of the whole day: the most famous Delyo of all, the Rhodope rebel of folk legend, is currently in interstellar space. The song about him, sung by Valya Balkanska, went out on the Voyager Golden Record in 1977, so a name-day boy called Delyo shares his celebration with a voice drifting somewhere beyond the solar system.

The full list runs to sixteen variants, taking in Neda and Nedyo, Nedka and Nedko, Nenka, Nenko and Nencho, and Neli and Nelina; the whole family is covered in our Bulgarian name-days guide. Readers check for their own names, so do have a look.

And the etiquette, because this is the bit that genuinely surprises Brits: on a name day the celebrant keeps open house. You do not wait for an invitation the way you would at home; friends, neighbours and colleagues simply turn up. The golden rule is never to arrive empty-handed: a cake, a banitsa, chocolates or wine all work, and if you bring flowers, an odd number only, since even numbers are for funerals.

Towns celebrating today

Rakitovo, a Rhodope town that counted just under 9,000 people at the mid-2000s census, holds its feast on St Nedelya's day. It sits 12 km east of Velingrad, the spa town, and about 7 km from the Batak Reservoir, in country that lives off timber and grows lavender, potatoes and barley; there is a small Aromanian community too. There is a neat historical echo here as well: these are the same Rhodopes that Alexius Slav ruled when he changed sides after the 1208 battle. If you fancy a look, the sensible day trip pairs the town's feast with Velingrad's mineral pools or an hour by the reservoir.

Why this matters for British expats

Philippopolis is not trivia; it is the name you meet all over Plovdiv, on the Roman theatre signage and half the hotels, and knowing that Crusaders and Bulgarian tsars once contested the plain below adds a satisfying layer to what is already the best weekend city break in the country. The name days are the practical end: with sixteen variants celebrating, the odds that a colleague or neighbour, in Shumen or anywhere else, is receiving guests today are better than usual. The greeting is честит имен ден (ches-TEET ee-MEN den), and a few more survival phrases live in our Bulgarian phrasebook. If you get the open-house invitation, remember the rules: turn up, bring something, count the flowers.

Sources and further reading

The battle account draws on the Bulgarian Wikipedia entry on the 1208 Battle of Plovdiv and its English-language counterpart; town detail comes from the English Wikipedia entry on Rakitovo, with the name days from the standard Bulgarian name-days calendar and the town feast from regional municipal listings.