The following is the Bulgarian order of battle at the start of the Second Balkan War as of 29 June [O.S. 16 June] 1913. This order of battle includes all combat units, including engineer and artillery units, but not medical, supply, signal, border guard and garrison units.

During First Balkan War Bulgaria mobilized 599,878 men out of a total male population of 1,914,160.^[1] Final victory over the Ottoman Empire however came at the cost of some 33,000 killed and 50,000 wounded soldiers while many others were affected by the spread of cholera and dysentery.^[2] With the end of the war the relations between the members of the Balkan League deteriorated rapidly due to the unresolved problem of the division of the conquered lands which forced Bulgaria to transfer its armies from Thrace to Macedonia.

On the eve of the outbreak of the Second Balkan War the field forces of the Bulgarian Army were deployed in five armies along a 500 kilometer front from the Danube to the Aegean Sea. Despite all the measures taken by the military authorities, including the drafting of young Bulgarian men aged 20–26 years living in the newly occupied territories in Thrace and Macedonia, the number of mobilized personnel reached a total of 500,491 men.^[3] Thus for the war against its former allies Bulgaria could rely on manpower that was about 83% of the one available during the First Balkan War.

The Bulgarian command deployed five field armies against Serbia and Greece while it kept minimal forces near the Ottoman border and no forces at all on the Romanian border. Besides the 11 infantry division, 1 cavalry division and the Macedonian-Adrianopolitan Volunteer Corps the high command also raised two additional infantry divisions(12th and 13th) and one independent infantry brigade. Many of the old divisions however had at least one of their infantry brigades taken away and attached to the field armies as independent units which created logistical difficulties. Thus it seemed the Bulgarian GHQ was attempting to provide greater numbers of available units while disregarding the quality of some of those units.^[4] As a result, the total strength of the field forces was increased to around 297 infantry battalions, 47 cavalry squadrons and 186 artillery batteries.^[5]

The material situation of the armed forces was improved compared to the first war. The number of available horses was increased by 12,594 to 97,456 while the number of rifles increased by 44,561 to 378,996 and artillery guns by 112 to 1228.^[3] Still according to the mobilization plans of the General Staff the army was supposed to have 483,674 rifles and 117,733 which showed that, like the manpower deficit, the material shortages had not been dealt with by the time the war began.^[3]

The nominal commander in chief of the Bulgarian Army was Tsar Ferdinand I but de facto its control and leadership were initially in the hands of his deputy Lieutenant-General Mihail Savov. The Chief of the General Staff Major-General Ivan Fichev opposed the war and was officially in resignation, though de facto he was never dismissed, while his functions were carried out by the Deputy Chief of Staff Colonel Stefan Nerezov . Other notable changes in the command structure took place almost immediately after the outbreak of the war when General Savov was fired as deputy of the commander-in-chief, although he latter returned to take command of the combined 5th, 4th and 2nd armies.^[6] Ferdinand chose the Russophile General Dimitriev as his deputy while General Racho Petrov assumed command of the 3rd Army.^[6]