From [the] September 1931 Manchurian invasion to the July 1937 outbreak of the Sino‐Japanese War, demand for nickel grew nearly tenfold.¹⁴ Conflict in China not only increased the need for nickel–steel armour plating but also raised the threat of American or British embargoes.

Without a domestic nickel supply, the [Imperial] Japanese army and navy relied entirely on deliveries from the British and American‐owned International Nickel Company of Canada (INCO); by 1929, INCO controlled nearly 90 per cent of the world market. This near monopoly, however, could be circumvented by importing nickel from New Caledonia, source of 7–8 per cent of world production.¹⁵

[…]

The [Third Reich] also benefited from these favourable economic and political conditions. Though German companies had no official presence in New Caledonia, the Krupp armaments manufactures relied on one German‐born, naturalized Australian businessman to arrange deliveries to their refinery in Frankenstein, Silesia. Louis Burkard first visited New Caledonia in 1935, staying for two months, and then returned in 1936.

The [Reich’s] commercial attaché in Tōkyō briefed Burkard on the various [Imperial] mining companies operating in New Caledonia and when a director of Sumitomo visited in November 1936, he spoke with Burkard, but avoided contact with SLN or local officials.²⁰ Burkard owned no mines and limited his activities to purchasing nickel and chrome ore from the independent miners. By 1939, one‐third of New Caledonian nickel exports had gone to [the Reich].²¹

New Caledonia offered [the Imperial bourgeoisie] one economic advantage unavailable to Germany: a handful of mining claims owned by local Japanese. A diverse Japanese community had emerged from several waves of indentured mine workers arriving between 1892 and 1914. After the First World War, these migrants successfully integrated with local French society, playing a significant rôle in the economy as miners, tradesmen, farmers and small business owners.

A short‐lived attempt by [Imperial] business interests to refine nickel in the colony from 1918 to 1920 laid the groundwork for two former Japanese employees of this venture to begin operating nickel and chrome mines in 1935.²²

A 1937 law designed to prevent a takeover of New Caledonian mineral wealth by foreign capital paradoxically further entrenched the [Imperial] mining interests, when they were forced to establish two French front companies (Société Minière de l’Océanie for nickel and Société Le Fer for iron) whose boards and management were nearly all members of the local colonial oligarchy.²³

By September 1939, [the Imperialists] had imported from New Caledonian mines 50,000 tons of nickel ore — nearly double the [Reich’s] imports — as well as over 100,000 tons of iron ore.²⁴ [Imperial] refineries had produced 1684 tons of nickel metal from that ore. Though this figure represented only 5 per cent of the total supply from 1936 to 1939, the strategy of domestic refining had succeeded.²⁵ By 1939, [Imperial] interests controlled 8946 hectares of New Caledonian mining claims with an estimated 14,650 tons of nickel content.²⁶

Thus, [Imperial] economic planners could imagine replacing their imports of Canadian nickel from INCO with domestically produced nickel metal from New Caledonian ore for the foreseeable future. [The Fascist] invasion of Poland in September 1939, however, set in motion a chain of events that disrupted this supply and ultimately influenced [the Imperial bourgeoisie’s] bargaining position in the negotiations leading to the Tripartite Pact.

[…]

So how did the [Imperialists] improve these relationships so quickly in July and August 1940? It is tempting to attribute this seeming about‐face solely to the French defeat and the arrival of the Vichy régime, but the Franco‐Japanese discussions about the May 1940 embargo on New Caledonian nickel show that before the [Fascist] victory, [Paris] had started to warm up to [Tōkyō] and had even floated the idea of renewing the Franco‐Japanese commercial agreement.

Similarly, with the arrival of the Vichy régime, Paul Devinat maintained his position as the director of economic affairs at the colonial ministry. Thus, he clearly appreciated the importance of the Franco‐Japanese New Caledonian trade relations before the fall of France and he pushed to maintain those relations under Vichy. Devinat then led the mission to Wiesbaden at the end of July 1940 to offer French colonial products in exchange for [Fascist] concessions.

(Emphasis added.)

Unfortunately, the author couldn’t help but take a few potshots at the Soviets (e.g. ‘Hitler’s surprising alliance with Stalin’ [sic]) for this writing, but if you can stomach those then this eighteen‐page article is an otherwise worthwhile read.