> Both of the things you mentioned, were things that Germany was forced into doing, as a matter of survival.
Germany wasn't forced into anything. They still had the option of not starting the war at all.
> ... but Belgium instead refused and actively tried to kill the German soldiers passing through. Hence why Germany then had to wage war against Belgium.
"Passing through"? They were invading. (Yeah, they were intending on just passing through, but they were still invading to do so.) Belgium was actively trying to kill German troops? Yeah, that's the way it goes when you march your army into another country without their permission. This is why Germany then had to wage war against Belgium? Putting troops across the border was already an act of war against Belgium.
Given that Germany insisted on starting the war by invading France, these were things that Germany was "forced" to do in order to have the best chance to win. But not invading France was actually an option.
"France entered World War I because Russia and Germany were going to war, and France honored its treaty obligations to Russia.[58]"
Not that Germany wanted to wage war against Russia either. Germany declared war against Russia because they declared war against Austria which had declared war against the Serbs who had assassinated their archduke.
"The event that was widely acknowledged to have sparked the outbreak of World War I occurred on June 28, 1914, when Archduke Franz Ferdinand, heir to the Austro-Hungarian Empire, was shot to death with his wife by the Bosnian Serb nationalist Gavrilo Princip in Sarajevo. Over the weeks that followed, Austria-Hungary blamed the Serbian government for the attack, hoping to use the incident as justification for settling the problem of Slavic nationalism in the tumultuous Balkans region once and for all. However, as Russia supported Serbia, an Austria-Hungary declaration of war was delayed until its leaders received assurances from German leader Kaiser Wilhelm II that Germany would support their cause in the event of a Russian intervention. ... Russia declared its intention to back Serbia in the case of such a conflict, Austria-Hungary went ahead with its war declaration against Serbia on July 28, one month after the assassinations."
"Germany warned Russia, still only partially mobilized, that to continue to full mobilization against Austria-Hungary would mean war with Germany. While insisting that Russia immediately halt mobilization, Germany began its own mobilization; when the Russians refused the German demands, Germany declared war on the czarist empire on August 1."
I don't mean to imply that Germany or any country is blame-free, but WW1 doesn't feature any clear cut good-vs-evil simplification the way WW2 does.
If I'm going to blame anybody, I'll blame Austro-Hungary for deliberately designing their ultimatum to be unacceptable to Serbia. Why did they do that? Because they wanted war with Serbia.
So Germany had to honor their agreement with Austro-Hungary, and therefore had to violate Belgium's borders? If they had displayed as much honor and integrity toward Belgium as they did toward Austro-Hungary, that would have been a good thing. It's not "behaving honorably" when you only do it toward some.
So Germany had the choice: Fulfill treaty obligations toward Austro-Hungary, or observe Belgian neutrality, or do both and be at greater risk of losing the war. Arguably, they chose what worked out to be the worst (at least, the most destructive) of the three options.
In hindsight, yes, every German from that era would have made different choices. However, at that time, it was hard to anticipate the extent to which other countries would involve themselves. The Germans of that time probably anticipated that at least one/some of the following would have occurred:
a) Serbia would give in to Austria's demands
b) Russia would not fully mobilize and commit itself so fully to war with Austria
c) In the event of war with Russia/France, Belgium would grant Germany right of passage, and remain neutral in the war
d) The UK would remain neutral in the war
e) USA would remain neutral in the war
Each of the above was a coin-toss in terms of likelihood, and if any of the above came up in Germany's favor, a long drawn out war would have been averted. Unfortunately for Germany, every one of those diplomatic outcomes went against them. Could Germany have made better decisions, with the benefit of hindsight? Of course. But I think it's unfair to portray them as evil villains, the way the Nazis rightfully are.
Austria didn't declare war against Serbs (the ethnic group), but it declared war and invaded Serbia (the country in which only a part of the ethnic group lived). Moreover, Gavrilo Princip wasn't even a citizen of Serbia but the citizen of Austria-Hungary, and the assassination wasn't sponsored by Serbia either.
An interesting data is that the invading Austrian army consisted in large part of ethnic Serbs from Bosnia that were serving in Austrian army.
Yes, Gavrilo Princip was a Serbian by ethnicity, like almost half of the population of Bosnia at the time, a then recently annexed province that was previously occupied by Ottoman Empire (Turkey). In fact, there probably was few ethnic Austrians in Bosnia, since Austria-Hungary was an Empire that simply treated Bosnia and many other similar regions as colonies. So, Gavrilo Princip was a member of an underground indigenous movement who was fighting the colonial power. It is debatable whether it is terrorism or not (one side's villains are the other side's heroes), but it is a historical fact that Serbia (the country) didn't instruct him, nor helped him, nor the assassination was in Serbia's interest. Simply put, the Austria was eyeing to invade Serbia for a long time before that, and used the assassination as a pretext for invasion that was going to happen sooner or later no matter what. Serbia accepted many outrageous Austrian demands, but Austria still invaded...
Germany wasn't forced into anything. They still had the option of not starting the war at all.
> ... but Belgium instead refused and actively tried to kill the German soldiers passing through. Hence why Germany then had to wage war against Belgium.
"Passing through"? They were invading. (Yeah, they were intending on just passing through, but they were still invading to do so.) Belgium was actively trying to kill German troops? Yeah, that's the way it goes when you march your army into another country without their permission. This is why Germany then had to wage war against Belgium? Putting troops across the border was already an act of war against Belgium.
Given that Germany insisted on starting the war by invading France, these were things that Germany was "forced" to do in order to have the best chance to win. But not invading France was actually an option.