alternatehistory.com

When Wilhelm I become king of Prussia in his own right in 1861 he faced a dispute with his parliament over the size of the army.

The parliament, dominated by the liberals, balked at Wilhelm's desire to increase the number of regiments.

However Wilhelm decided after much thought to use their own liberalism against them.
He went to the Prussian parliament with his desire to crush slavery saying that this was what the additional regiments were for.
He stated that a line must be drawn in the sand and as good Christians, Prussia must help the United States of America put down the revolt with the slave owning south.

The Prussian parliament was in a quandary they didn't want a larger army yet they didn't like the idea of slavery either.

In a close vote the Prussian parliament voted to approve the additional regiments but only until the slave states in the US had given up their pro slavery stance.
By September of 1861 the Prussian government formally offered the government of the United States of America direct military assistance.

It was an offer that was quickly accepted by President Lincoln and a new friedship was born.
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