What invention sparked an increase of
Slave labor?

The cotton Gin by Eli Whitney sparked an increase in slave labor

Explanation:

Slavery was integral to the United States' transformation from a nascent conglomerate of colonies to a global economic powerhouse over the course of less than a century. In the mid-19th century, nearly 60 percent of the country's exports consisted of cotton produced through slave labor.

But a new set of maps from Radical Cartography shows just how much slavery exploded in the US, due in large part to the invention of Eli Whitney's cotton gin, which sparked the beginnings of the Industrial Revolution.

what are the issues?

it would be  

germany had to pay all damages related to the war.

and i think

germany had to take sole responsibility for the war.