Complex sentence: In January 1942 he recorded the arrival of American troops in Northern Ireland and in March of that year he went to Cairo and joined the British First Army on its march to Tunisia and then joined the Eighth Army.
Split into simpler sentences: In January 1942 he recorded the arrival of American troops in Northern Ireland. In March of that year he went to Cairo and joined the British First Army on its march to Tunisia, and then joined the Eighth Army.