Filon Kmita was notable for conducting counter-intelligence in the Muscovite wars and establishing a spy network in the Grand Duchy of Muscovy, as well as successfully leading ambush attacks with considerably fewer soldiers than the enemy.

Kmita would also be noted for his excellent organizational skills and fast attack into the Muscovite lands in the summer of 1579, at the same time as commander Krzysztof Radziwiłł almost captured the Russian ruler.

In 1580, Kmita was mistaken by a message of a double agent and attempted to take over the strongest Muscovite fortress - Smolensk - with only 9,000 soldiers but failed.

Once Kmita captured the city of Orsha, he made it the center of his intelligence operations, which he would use to receive information about the movement of Tatar or Muscovite units.

Such useful information via secret letter Filon Kmita would send back to the Lithuanian Council of Lords as well as the rulers of Lithuania, Poland, and the most notable of nobles at the time.

Kmita himself wrote some letters to tsar Ivan the Terrible dedicated to further incite paranoia among the enemy circle, which also according to the theory supposedly lead to the sack of Novgorod.