He completed the studies in law in Vienna and attended lectures at the prestigious Ecole de Droit in Paris.

He published essays and articles in Kranjčević's Nada and literary magazines in Zagreb, where he was employed at the Royal Court Table.

He published the brochure Josip Štadler and the Croat People's Union (Sarajevo, 1908), which was opposed by the clergy and provoked a political rift between him and the Archbishop of Vrhbosna.

In his brochure, Pilar concluded that the Catholic faith had undoubtedly an exceptional role in preserving the national identity of Croats in Bosnia and Herzegovina, but he believed there were certain differences between the interests of the people and the Church as an organisation.

In 1910 he founded the Croat People's Union, trying to politically awaken impassive Croatian Catholics and prepare them for the incoming portentous events.

While many Croats eagerly awaited the dissolution of the hated Austro-Hungarian Monarchy, Pilar warned that it was the only guarantee for a Croatian identity and that the country had to be reformed, but not destroyed.

The developments in the Transleithanian part of the Monarchy were going against Pilar's wishes and beliefs, so he published a booklet of 32 pages in Sarajevo in 1918.

The full original title of the work in German language was: L. v. Südland, Die südslawische Frage und der Weltkrieg.

It was translated, arranged and commented by the industrious South Slav expert Fedor Pucek and published by Matica hrvatska.

Hrvatima oteše današnju zapadnu Srbiju, nekadašnju Duklju, a jedna od glavnih sila koja je dovela do današnjeg rata (Prvi svjetski rat - S.T.

), jest zagriženo nastojanje Srba, da Hrvatima konačno otmu i Bosnu i Hercegovinu [The Serbs] took from the Croats modern-day western Serbia, that is ancient Doclea, and one the main forces that brought to today's war [First World War] , is the continuous seeking of the Serbs, to finally snatch away both Bosnia and Herzegovina too from the Croats.

The press in Belgrade claimed it was a suicide, but the open window of his apartment and the fact that Pilar never owned a weapon made his death suspicious.