As David Cameron told us at the launch of the centenary, almost every family in the UK was affected by the war. It also had a transformative effect on the Labour party. At the outbreak of hostilities, there was a real danger it would fracture the party in two. However, when the guns finally fell silent in 1918, Labour had become a force to be reckoned with in British politics, with MPs who had served in the Cabinet and had direct experience of running a managed economy. In the first election following the conflict, Labour tripled its vote share, and a scant five years later formed a government for the first time.

Labour’s tumultuous route through the First World War well demonstrates the party’s fractious attitude towards armed conflict. One hundred years on from that tragedy now is a good time to reflect on Labour’s relationship with war.

One myth that needs busting from the get-go is that Labour was, and is, the party of pacifism. In 1914, it is true that Labour was split between pro-war and anti-war supporters, but the former far outnumbered the latter, according to historian Martin Pugh. In fact, the National Executive Committee voted in support of the war, although the Independent Labour Party (ILP), a key faction in the nascent Labour movement, remained opposed. More importantly, as Pugh explains, “much of the rank and file…supported the war”.

While socialists always strive for peace, recognising that violence is the last recourse of civilised nations and that war inevitably harms the poorest the greatest amount, those early members of the Labour party were also realists. J.R. Clynes, a popular member of the ILP, explained that his pro-war stance was “consistent with the actions of a socialist when the choice is no longer between peace and war, but between peace and submission to the warmaker”.

Fast forward 100 years, and the party’s sentiment towards war- both in the Parliamentary Labour Party and the grassroots- has changed. The Iraq War, where, despite the threat posed by Saddam Hussein to his own people and those around the world, the UK and US were unquestionably the ‘warmakers’, has altered our appetite for conflict.

So are we now a party of pacifists? Labour’s opposition to military intervention in Syria would suggest so; but let’s remember that Ed Miliband whipped the party behind the action in Libya in 2011. Where the case for a ‘just war’ against a hostile regime is proven Labour should not be afraid of supporting armed intervention. Socialists are believers in the inviolability of human rights and should be ready and willing to oppose those who are not.

The First World War also gave the lie to those who accused Labour of being unpatriotic. Socialists were then, and still are today, suspected of being a treasonous bunch desperate to topple the establishment and build a communist dystopia in its place. However, during the war many Labour MPs came to realise the powerful influence king and country held over the working classes. James O’Grady, Labour MP for Leeds during the war, even went so far as to say the establishment of socialism would go hand in hand with nationalism. In fact, Pugh’s history suggests that the First World War cemented Labour’s popularity with working class conservatives- patriotic, monarchical, and imperialist men and women whose votes helped propel the party to power in the early twenties.

Today, we are all rightly wary of where unchecked nationalism can lead. However, that does not mean Labour should be afraid of being patriotic. The Young Fabians are exploring One Nation Labour and patriotism this year. Meanwhile, at a national level, Ed Miliband has been strident in his calls for a renewed sense of pride in our national identity. Labour cannot allow the Tories to gain a monopoly on the Union Flag. In the trenches, socialists fought for that flag as fervently as their conservative and liberal brothers-in-arms. In parliament now, Labour should remember the crucial role patriotism played in the party’s rise to power.

The First World War holds lessons for all of us, even a century on. Labour should remember its heritage when it comes to armed interventionism and patriotism. Forgetting the past will only lead to a bleaker future.