In the Interwar Period, Marjanović travelled to the United States, organising exhibitions of works of sculptor Ivan Meštrović and attending a course in photography and film directing in New York.

A significant portion of Marjanović's writing dealt with the works of Silvije Strahimir Kranjčević, Ante Kovačić, and Vladimir Nazor.

[2] During the Croatian National Movement of 1903 [hr], Marjanović printed and distributed the so-called Basel Manifestos urging the population of Croatia-Slavonia to resist magyarisation policies of the Ban of Croatia Károly Khuen-Héderváry.

[3] Marjanović spoke at the Zagreb Assembly held in protest against Khuen-Héderváry on 11 March 1903,[3] calling on those present to use peaceful means until those are exhausted, then, if necessary, force.

He was accused of involvement in the 1912 attempted assassination of the Ban Slavko Cuvaj and was forced into exile in Belgrade where, as a hired correspondent, he wrote articles on the Balkan Wars for several foreign newspapers.

Following the 1914 assassination of Archduke Franz Ferdinand in Sarajevo, Marjanović was confined to Kastav, and then imprisoned in Ljubljana and Zagreb, before being sent to Karlovac prior to being drafted at the onset of the World War I.

In 1912, inspired by Serbian military victories in the Balkan Wars, they established the Yugoslav Nationalist Youth (Jugoslavenska nacionalistička omladina, JNO) and denounced the parliamentary political struggle advocated by the coalition.

Conversely, he opposed the non-democratic and non-national practices of those living in the Pannonian Basin, specifically in central and eastern Croatia.

[6] In his collection of essays Narod koji nastaje: zašto nastaje i kako se formira jedinstveni srpsko-hrvatski narod (A Nation in Becoming: Why and How is a Unified Serbo-Croatian Nation Being Formed) published in 1913, Marjanović claimed that the Ottoman conquests in Europe both destroyed the medieval South Slavic kingdoms and stopped the formation of separate nations—creating an amalgamated South Slavic population.

[7] The variant of integral Yugoslavist ideology based on Cvijić's and Marjanović's work was subsequently adopted by the pro-regime Organization of Yugoslav Nationalists founded shortly after establishment of Yugoslavia.

He followed the ideas of Vissarion Belinsky, Hippolyte Taine, and Georg Brandes, examining literature through the Tomáš Masaryk's utilitarian prism of social realism.

A sizeable portion of Marjanović's writings dealt with the works of Silvije Strahimir Kranjčević, Ante Kovačić, and Vladimir Nazor.

Marjanović also wrote plays, including one based on Kovačić's work, U registraturi, a novel and a series of political and literary-culture articles.

'Occultism and Esotericism'), and Načela i forme, dužnosti i odnosi, zadaci i metode slobodnog zidarstva uopće, a jugoslavenskog napose (lit.

They include films documenting the sculpting of Meštrović's The Bowman and The Spearman, and unveiling the same sculptor's Gregory of Nin [hr].