Settlement in the area escalated enough during the early 1910s to warrant postal services. The Armada Post Office officially opened on January 1, 1915, operating out of a local country store. The community's first postmaster was E.E. ("Bert") Saunders, who managed the post office from his store until 1917. He was later succeeded by William Edward Howell in 1918, who ran operations for decades.

Before a railway reached the immediate area, mail had to be actively couriered from nearby Vulcan. For its first decade, Armada remained a modest crossroads community. However, the economic viability of the hamlet shifted dramatically when the railway arrived in 1924, providing a reliable way to ship regional grain to external markets. With the railway securing its status as an agricultural shipping point, local infrastructure grew. A school was established in the community by the 1930s (specifically noted around 1937), alongside grain elevators and local trading spots that serviced the surrounding farm families who had claimed homesteads under the Dominion Lands Act.

Like hundreds of other small prairie hamlets across Alberta, Armada's decline was driven by structural shifts in agriculture, transportation, and rural economics, As automobiles became widespread and rural populations consolidated, smaller local post offices became redundant. The Armada Post Office officially closed on July 15, 1959.