Complex sentence: Under the pressure of the queen-mother, the Guises agreed to consult with the notables leading to the assembly of notables that met in Fontainebleau from August 21 to 26.
Split into simpler sentences: Under the pressure of the queen-mother they agreed to consult with the notables. This led to the assembly of notables that met in Fontainebleau from August 21 to 26.