Not all holidays involve parades, and not all parades happen because of a holiday. But there’s enough overlap for this to seem like a suitable place to take a look at processions of all kinds.
Where’s the line between processions and parades? I don’t think there really is one, as they both involve long trains of people making a journey between two points. This may involve vehicles ranging from horses to carriages or cars to enormous Rose Parade floats, and many of them include music, partly as a means of keeping everyone energized and together. The two terms are more of a spectrum, with “processions” at the solemn end of the spectrum and “parades” at the raucous end.
But what types of occasions get what type of event really depends on the culture. In the West, for example, a funerary cortege is usually a somber procession, with participants on foot or in vehicles heading slowly for the church or the cemetery. If you attend a jazz funeral in New Orleans, though, you’ll find music and dancing — because that’s drawing on the traditions of enslaved Africans alongside Christian Europe.
In fact, while the influence of Protestantism tends to make religious events in the West fairly sedate, that’s hardly inherent to the idea of spiritual celebration. Catholic celebrations are often livelier, and in Japan, most Shintō matsuri (festivals) are such energetic affairs that the bigger ones get actively marketed for tourism purposes. These involve taking the divine vessel of a kami out and placing it in an elaborately decorated palanquin which is then carried through the streets, sometimes being shaken around for the kami’s amusement, sometimes engaging in mock battles with parades from other shrines. Nowhere is the lack of solemnity more obvious than in the famous Kanamara Matsuri, where the thing being carried around town is a giant carved penis — complete with penis candy being sold in roadside stalls.
Parades and processions aren’t exclusively a religious thing, of course. They’re also heavily linked with both government and the military (which makes sense when you consider how intertwined those three things often are anyway). Rome famously had its “triumphs,” where a victorious general might be granted the honor of a procession through the city before offering sacrifice at the Temple of Jupiter on the Capitoline Hill. This was very much a political maneuver as well as a spiritual one, boosting the general’s status, making him known to the city’s populace, and showing off the might of Rome to any foreigners who might be watching.
I could be wrong about this, but my impression is that formal military parades are heavily linked to having a standing, professional army. For them to seem impressive, you want things like uniforms and enough training to maintain an organized block on the move (which anybody who’s ever been in a marching band will tell you takes more than just the ability to walk in step). A motley herd of conscripted peasants holding rusty blades and repurposed farm implements doesn’t really project the sense of power a military parade is supposed to create. A well-dressed and well-equipped array of soldiers, on the other hand, says “we have the experience, training, and discipline to crush anyone who stands in our path” . . . and that light reflects on whoever that force answers to.
Speaking of displays of power, there’s a European concept called a “royal progress” (mentioned in one of my favorite lines from Hamlet, where he talks about worms and “how a king may go a progress through the guts of a beggar”). In the days before mass communication, the monarch could be a very distant figure, identifiable only through their profile on a coin, and not even that when the economy wasn’t very monetized. In order to make themselves more known to their subjects, and to keep tighter control over government in the outlying parts of their realm, they would undergo long journeys to visit various nobles and settlements in person.
Even in the countryside, the progress would be impressive, simply because it was such a large collection of people and carriages and wagons and so forth. But upon entry to a town or city, this would form up into a dazzling array, granting people the chance to see their sovereign in all his or her glory. And hosting the progress was a great honor . . . but one that was sometimes used to control potentially fractious vassals, as they had to bear the costs of hosting, which could neatly put an end to any hope of financing a rebellion.
Elements of this kind of parade survive in modern times, too, even though we have TV and so forth to make our leaders very familiar to us. I bring this up in part to highlight the risks of such a thing: both John F. Kennedy and Archduke Franz Ferdinand of Austria were assassinated while riding in a motorcade, in open-topped cars meant to let people see the visiting dignitaries. There’s still a charge inherent in seeing someone or some group in person, as opposed to on a screen. Because of this, the surrounding elements of a parade — military guards especially — aren’t just an expression of power and a display of wealth; they also serve as a buffer to (hopefully) keep danger away from the guest of honor.
Mind you, parades can also be turned against power, in the form of a protest march. Doing something like this can be incredibly dangerous in a society where citizens aren’t guaranteed the right to assemble in groups and express their views; unauthorized marches stand an extremely high risk of being broken up by armed response, with possibly fatal results. Even authorized events can be dangerous, if the police decide the crowd is getting “too rowdy” and start to crack down.
Any parade that’s about more than just a mob of people spontaneously coalescing needs a certain amount of planning. You need to gather people together at a set time and location, which might take quite a bit of advance preparation if communication and travel are difficult; this part is much easier for regular annual events like religious parades. You need to choose a route, because for the parade to remain cohesive, you’ve got to clear the way and keep routine traffic from interfering (and if possible, avoid blocking said traffic up so thoroughly that it screws over everybody’s day). In a bureaucratic society, you want that authorization I mentioned before, to get assistance in that route-clearing and avoid clashes with the people in charge of maintaining order. Whether you expect trouble or not, it can be a good idea to put support structures in place, with water and first aid for anybody who suffers a problem along the way. It’s a lot of work!
But if you do it all right, you end up with a truly glorious display.