Andrianjaka obtained a sizable cache of firearms and gunpowder, materials that helped to establish and preserve his dominance and expand his rule over greater Imerina.
[citation needed] Andrianjaka was also actively involved in providing support to his father's military campaigns to expand and defend Ralambo's realm.
[1] Andrianjaka reportedly suggested an innovative defensive tactic to annihilate the enemy by filling the town's hadivory (defensive trenches) with cow dung and rice husks, lighting it on fire, and covering the smoldering embers with burnt rice stalks so that the area resembled a patch of land recently re-cleared for planting through tavy (slash and burn agriculture).
During this delay, his older brother Andriantompokoindrindra received his father's message and rushed home; he was thus awarded Ralambo's title and kingdom.
[4] One source states that the summons was not a test, but rather occurred during the aforementioned incident when Ralambo was besieged in his capital by the Antsihanaka warriors and was genuinely in need of his sons' assistance.
[2] He unified the principalities on what he later designated as the twelve sacred hills of Imerina at Ambohitratrimo, Ambohimanga, Ilafy, Alasora, Antsahadita, Ambohimanambony, Analamanga, Ambohitrabiby, Namehana, Ambohidrapeto, Ambohijafy, and Ambohimandranjaka.
[11] Around 1610[12] or 1625[citation needed] according to various estimations, Andrianjaka commanded a garrison of 1,000 soldiers to seize the hill of Analamanga ("Blue Forest")—at 1,480 metres (4,860 ft) above sea level, then the highest and most strategically important in the region[13]—from its Vazimba inhabitants.
[2] He reportedly succeeded with minimal bloodshed: according to oral history, the encampment of his army at the foot of Analamanga was sufficient to secure the submission of the Vazimba.
[8] This feat was accomplished by mobilizing large numbers of his able-bodied subjects to construct dikes that enabled the redirection of rainwater for controlled flooding of planted areas.
[16] According to one account, the very first royal house constructed within the Rova of Antananarivo was named Besakana ("Great Breadth") and served as the personal residence of Andrianjaka.
[19] Sovereigns were enthroned in this building and their mortal remains were displayed here before burial,[20] rendering Besakana "the official state room for civil affairs... regarded as the throne of the kingdom.
[2] According to oral history, the institution of lengthy formal mourning periods for deceased sovereigns in Imerina may also have begun with the death of Andrianjaka.