How did the growth of alliances lead to tension in europe

If this is pre-WWI, then I'd say it is because everyone, well mainly the smaller countries, where quick to call their "big brother" or largest alliance holder to help them when a problem faced them, threating like a small child would say " Stop, or i'll call my big brother to beat you up! "

“destroyers for bases agreement in the destroyers for bases agreement between the united states and the united kingdom on september 2, 1940, fifty caldwell , wickes, and clemson class us navy destroyers were transferred to the toyalbnavy from the united states navy in exchange for land rights on british possessions.” i hope this you .