With the colonization of Madeira and the Azores, the foundations were laid for the future Portuguese empire.
When the Portuguese colonized Madeira and the Azoras, it signaled the end of their empire. 
mnli hypothesis: When the Portuguese colonized Madeira and the Azoras, it signaled the end of their empire.  premise: With the colonization of Madeira and the Azores, the foundations were laid for the future Portuguese empire.