In the post-war years the company continued to operate as a commercial strategic reserve until 1984 when, as a result of taking on a series of expensive long-term time charters, it was forced into liquidation.

Ireland had declared its neutrality when hostilities broke out and in the early years of the war much of its food needs were carried on board Allied ships.

In February 1941, Seán Lemass, the Minister for Supplies stated that "The creation of an Irish mercantile marine was necessary, as it was as important for the national safety as the Army".

On 21 March 1941, Irish Shipping Limited was formed as a company majority owned by the state, which held 51% of the shares.

It had been abandoned following an attack by a German aircraft in the Bay of Biscay and towed into port by Spanish fishermen, where it was purchased by Irish Shipping.

This led it into a number of other commercial ventures, most notably marine insurance and ship repair, where it might not necessarily have wanted to be.

Irish Pine was the first of six ISL steamships whose triple-expansion engine was augmented with an exhaust steam turbine, which increased both power and fuel-efficiency.

The Irish Holly was primarily a coastal oil tanker, triple expansion steam engine.

The Irish Plane operated on the Casablanca – Dublin – Cork run, importing phosphate fertiliser for several years.

She was designed to run with an unmanned machinery space, UMS, for night time sailing in open waters, however this was seldom, if ever achieved.

The ships was primarily designed as a bulk carrier, but had electro-hydraulic cranes and pontoon decks fitted after her sea trials.

A further mis-match of technology was the use of steam driven reciprocating feed pump for the exhaust gas boiler.

In the early 1970s ISL set up a joint venture with Reardon Smiths called Celtic Bulk Carriers and between them ordered 12 standard ships from Govan Shipbuilders in Glasgow.