Why was the assassination of franz ferdinand the "spark" but not the full cause of ww1

The Franz Ferdinand assassination was not the cause of war. Tensions between the Great Powers of Europe had been rising gradually since the beginning of the 20th century and it is entirely feasible that a Great War would have taken place had the Archduke not been murdered.

This act gave the federal government the power to relocate any native in the east to territory west of the mississippi river.

My best answer is the haudenosaunnee or the iroquois.