Portugal sent what it could, being Britain's oldest ally. The alliance actually dated from the time of Prince Henry the Navigator and it went very much both ways; when Portugal and Spain were invaded by Napoleon, the British sent an army; the result is called the Peninsular War. It is from the Peninsular War that we get such things as Rifle regiments -- two of them -- the first Rifle regiments to be raised; we also get the "Sharpe" books and videos.... and the word "guerrilla".
When the Great War broke out, Portugal sent what it could raise, which amounted to ONE battalion of men, armed with Vergueiro rifles which took the 6.5x58 cartridge..... which was only being made in Germany. Britain designated this single battalion as the "Portuguese Brigade" as a face-saving matter..... and supplied the Portuguese troops with such things as Lee-Enfields (traded for the Vergueiros, which ended up on South Africa, closer to a supply of Portuguese ammunition in Angola), Vickers guns, Lewises when they began to become available, steel helmets, rations, better boots, gas masks (once they were invented) and the remaining tools of a modern war. Later, when Portugal sent enough men to actually CLAIM a Brigade, the British changed the name to the Portuguese Division.
There is no doubt that the manpower was good and the Portuguese soldiers as brave as any; they just got very little ink from the media of that time.... and this oversight has continued to this day.
We SHOULD give honour to our Portuguese allies; they certainly PAID enough for it!