Born into an Armenian-Hungarian noble family, Lázár began his military career in 1834 when he entered the service of the 34th infantry of the Imperial army.

Emperor Ferdinand I commissioned him as a second lieutenant in the Hussar regiment, but in 1844 he retired from a military career and returned with his wife, Baroness Mária Revitzky to his estate farm in Zemplén.

At the end of the month the brigade was reassigned to the legion forming in Kassa (present-day Košice), Upper Hungary and he was promoted to a higher position.

He split from Arisztid Dessewffy and headed towards Hátszeg (present-day Hațeg), but on 19 August along with the remainder of his legion (4,600 people) he had to lay down arms in front of the imperial troops.

Although Lázár only attained the rank of colonel, as a separate corps commander in the War of Independence he was considered to have equal status with the generals in the Arad military court martial.