Domino effect that occurred after Austria declared war against Serbia?

Answer 1

The Austro-Hungarian government used the assassination of Archduke Franz Ferdinand as a pretext to deal with the Serbian question, supported by Germany. On 23 July 1914, an ultimatum was sent to Serbia with ten demands, some so extreme that the Serbian reply included reservations and rejected the sixth demand. The Serbians, relying on support from Russia, removed acceptance of the sixth key demand (the draft reply had accepted it), and also ordered mobilization. In response, Austria-Hungary issued a declaration of war on 28 July. Initially, Russia ordered partial mobilization, directed at the Austrian frontier. On 31 July, after the Russian General Staff informed the Czar that partial mobilization was logistically impossible, a full mobilization was ordered. The Schlieffen Plan, which relied on a quick strike against France, could not afford to allow the Russians to mobilize without launching an attack. Thus, the Germans declared war against Russia on 1 August and on France two days later. Germany then violated the neutrality of Belgium by advancing through it on the way to Paris. This brought the British Empire into the war, as Britain had guaranteed Belgium's neutrality in treaties arising from the Belgian Revolution of 1830. With this, five of the six European powers were now involved in the largest continental European conflict since the Napoleonic Wars.[34]

This is a bit easier to understand:

Austria blamed Serbia for Ferdinand's death and declared war on Serbia.

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Germany pledged their support for Austria - Hungary.

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Russia pledged their support for Serbia.

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Germany declares war on Russia.

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France pledged their support for Russia.

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Germany declares war on France.

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Germany invades Belgium on the way to France.

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Great Britain supports Belgium and declares war on Germany.