 Complete the following phrase:  During his short reign the Byzantine emperor Alexander r. 912913 provoked a conflict with the Bulgarian monarch Simeon I r. 893927. Simeon I, who had long harboured ambitions to claim an imperial title for himself, took the opportunity to wage war. With the Byzantine Empire in disarray following Alexanders death in June 913, the Bulgarians reached Constantinople unopposed and forced the regency of the infant Constantine VII r. 913959 to recognize Simeon I as emperor in Bulgarian, Tsar. Following a palace coup in 914, the new Byzantine regency revoked the concessions to the Bulgarians and summoned the whole army, including the troops in Asia Minor, to deal with the Bulgarian threat once and all. In the decisive 