The language Vuk had to defeat first
Vuk Karadžić's opponents were not defending chaos. They were defending an entire literary language - slavenosrpski, a hybrid of Church Slavonic, Russian and Serbian vernacular that had its own grammars, its own authors and, for most Serbs who could read at all, absolutely no relationship to how anyone actually spoke.
Vuk Karadžić's reform is usually told as a story about spelling - thirty letters, one sound each, write as you speak. That story needs a villain, and the villain is usually left vague: "the old way of writing", as if the alternative were simply carelessness. It was not. Before Vuk, educated Serbs wrote in a real literary language with a name, a body of published work and a generation of writers who considered it the only proper vehicle for serious prose. It was called slavenosrpski, and understanding what it actually was explains why the fight over replacing it lasted the better part of a century.
Serbs without a press of their own
After the Great Migrations of 1690, large numbers of Serbs left Ottoman territory and settled in the Habsburg Monarchy - what is now Vojvodina. They arrived with a church and a language but with almost no printing infrastructure of their own, and Ottoman-ruled Serbia to the south had even less. When the Serbian Orthodox Church needed liturgical books, it turned to the one place already printing them in a related Slavic idiom: Russia. Russian Church Slavonic texts, in the Russian civil script and spelling conventions of the day, flooded Serbian churches and schools through most of the eighteenth century.
That is the detail that matters: the first model of "correct" written Slavic that educated Serbs absorbed was not their own vernacular, written down. It was somebody else's language, borrowed wholesale because no local alternative existed.
A different mixture on every page
Slavenosrpski was not a codified standard with a grammar book behind it. It was a working compromise, assembled sentence by sentence: Church Slavonic supplied the grammatical scaffolding and the vocabulary of anything solemn or abstract, Russian supplied civil and scholarly vocabulary that Church Slavonic itself lacked, and everyday Serbian filled in whatever neither of the other two had a word for. No academy fixed the proportions, so the mixture depended entirely on the individual writer - how much Church Slavonic he had studied, how much Russian he had read, how comfortable he was letting plain Serbian show through.
The practical result was a written language that shifted register from paragraph to paragraph and differed from author to author, close enough to Serbian for a literate person to make out the general sense, and foreign enough that reading it fluently - let alone reading it aloud correctly - was a skill acquired over years of schooling, not something a village-educated speaker of Serbian could simply do.
Vuk was not the first to object. Dositej Obradović (1739–1811), a Serbian Enlightenment writer who later became the newly independent state's first Minister of Education, had already argued decades earlier that Serbian books should be written for ordinary people to understand, not for scholars to admire. But even Dositej stopped short of Vuk's later position - he softened slavenosrpski rather than abandoning it. Vuk's break was more radical: not less Church Slavonic and Russian, but none at all.
Why a demotion felt like one
To Vuk's opponents, the demand to write in plain vernacular Serbian was not a simplification - it was a demotion. Slavenosrpski was the mark of an educated Serb, proof that its writer had studied Church Slavonic grammar and read Russian scholarship, and it visibly distinguished the literate class from villagers and their oral folk songs. Being told to write the way a shepherd talked felt, to a generation of scholars and clergy, like being told their education did not matter. That is why the dispute was fought for decades, in journals and pamphlets, long after Vuk had already published the collections of folk poetry that made his case for him.
Danas idem kod bake na ručak.
Today I'm going to grandma's for lunch.
An ordinary sentence, exactly the register slavenosrpski's writers considered beneath literature - every word in it is plain inherited Serbian vocabulary, nothing borrowed from Church Slavonic or Russian, nothing that needs a gloss. This is the entire argument Vuk was making: that a language capable of this needed no dressing up to be a literary one.
What actually survived
Vuk's side eventually won - his orthography became Serbia's official standard in 1868 - but slavenosrpski did not vanish without a trace. Church Slavonic kept, and keeps, a narrow role inside Orthodox liturgy itself, untouched by any secular spelling reform. And the instinct that made educated nineteenth-century Serbs reach for a heavier, more Latinate-or-Slavonic-flavoured word in serious writing has a distant descendant in modern Serbian's own formal and academic register - a choice of vocabulary for solemnity that a beginner never needs, and a fluent reader eventually learns to recognise.