As most people know, the spark that led to WW1 was Austrian-Hungarian monarchy's invasion of Serbia. This is usually portrayed as a bloodthirsty and warmongering Austria-Hungary trying to dominate Serbia. However, this video gives a different perspective:
The summary is that the Black Hand in Serbia was used as a base of operations for carrying out terrorism in the Austria-Hungary. They couldn't really do much about it because they had no sovereignty over Serbia, so they could just carry out their terrorism and go back under the safety of Sebria. While there is no direct evidence the Serbian government was directly involved in Black Hand terrorism, it certainly appears that they were covering for them. The best case scenario seems to be that they were just plain incompetent in their handling of the situation, and that's being generous. The ultimatum given to Serbia is usually portrayed as completely unreasonable and just an excuse for war. But looking at the context, it appears to be less unreasonable than usually assumed.
I didn’t watch the video, so maybe this is mentioned, but Austria-Hungary issued an ultimatum to Serbia in the aftermath of the assassination of Franz Ferdinand that consisted of ten demands. Nine of these demands were submitted to. The one it did not submit to — although it agreed to submit the matter to arbitration — required Serbia to allow Habsburg authorities to conduct their own investigation on Serbian soil, which many considered to be a compromise of Serbia’s sovereignty.
Notably, Serbia agreed to crack down on the Black Hand’s parent organization (called People’s Defense), so I don’t think it’s fair to say that the Serbian government was covering for them. Further, relations between People’s Defense and the Serbian government had soured by 1914. Serbia had no reason to protect organizations endangering its own security.
After the assassination of Archduke Franz Ferdinand, the heir to the Austro Hungarian throne, Serbia was viewed as a significant threat. The assassination took place in Sarajevo, Bosnia, which had been annexed by Austria-Hungary in 1908 which angered many Serbs and fueled nationalist movements. Austria-Hungary believed that Serbia was directly involved in fostering anti-Austrian sentiments and encouraging terrorism through the Black Hand, a secret Serbian nationalist group.
From an international perspective, Austria-Hungary’s response was seen as a disproportionate response to the assassination of Franz Ferdinand. While tragic, the assassination was not necessarily a direct act of war that warranted such a large military response.
While Austria-Hungary may have believed it was justified in taking action against Serbia due to its perceived support of nationalist terrorism and destabilization of the region, the invasion was widely seen as an overreaction and one of the key factors that led to the outbreak of World War I.
International law was still developing at the time and was even less formalized than it is today. There were key principles, but they were not always applied uniformly or universally. It emphasized the sovereignty of states and their right to self-determination, meaning each nation had the right to govern itself without external interference. This principle was enshrined in earlier treaties and customs, such as the Westphalian System (1648), which established the importance of respecting state borders and internal affairs.
There was little in place to prevent the aggressive actions taken by Austria-Hungary against Serbia. The lack of strong international institutions to mediate or resolve disputes contributed to the rapid escalation into World War I. The war itself eventually led to the creation of the League of Nations and the establishment of more formalized rules of international law through the Treaty of Versailles and later frameworks for global diplomacy and conflict resolution.