Answer:
 Germany was lagging behind many countries, mostly Britain in the arms build-up. Germany wanted to grow out their militarism to either keep its nation safe or to expand, all for its self-benefit. It was also to show that Germany was capable of independence from the network of allies they had. 
(Counter:) 
However, since one country had joined an alliance with others, their military powers would be combined and would've had a bigger impact than a single country. The network of alliances let nations help each other in war and with this extra power, they were able to control and have more power against a single nation.