Initially active only in Central Poland, the PMO units in time were formed in all parts of the former Polish–Lithuanian Commonwealth, including what is now Lithuania, Belarus, Ukraine and Russia.

It was mainly preoccupied with intelligence and sabotage, as well as military training of its members and the acquisition of arms from various armies fighting on Polish soil.

After most of Poland was occupied by the Central Powers in 1915, the PMO became semilegal and unofficially supported by the German army, which saw it as a useful source of information on Russia and a useful reservoir of skilled officers.

However, in July 1917, after the Oath Crisis in the Polish Legions and the arrest of Piłsudski, the PMO returned to the underground and started covert operations against German and Austrian garrisons and supply lines.

In place of Piłsudski, who was sent to a German prison in the fortress in Magdeburg, the commander of the PMO became his friend Edward Rydz-Śmigły, who was also a future Marshal of Poland.

The campaign was successful and gave the newly born Polish state a large quantity of arms and military equipment.

Contrary to the rest of units, the PMO in Ukraine (most notably, the areas controlled by the Western Ukrainian government and or the Kiev-based Directorate and Hetmanate) remained active after the Polish withdrawal from Kiev in July 1920.

[1][2] From the documents that were stolen in its headquarters safe in Vilnius and given to Prime Minister of Lithuania Augustinas Voldemaras, it is clear that the plot had been directed by Piłsudski himself.