Rome was angered by Menelik's stance and ordered the Italian governor of Eritrea, General Oreste Baratieri to retaliate. He captured Adigrat, Adowa and Makalle from the Ethiopians and was feted as a hero in Italy. The Italians seriously underestimated the Ethiopians thinking that they were barbarians who needed Roman civilization and Bartieri returned to Eritrea after boasting that he would bring Menelik back in a cage. By this time Menelik had assembled 196 thousand men in Addis Abeba. Over 50% of these were armed with modern rifles. General Bartieri could only muster 25 thousand men and when he realised that he was outnumbered he retreated to Adigrat where he was beseiged by Menelik for 45 days. Menelik's gift of safe passage to the Italian garrison and offer to negotiate only infuriated Rome, and the Crispi government sent reinforcements and more money to continue the war.

Instead of attacking as Baratieri hoped he would, Menelik concentrated his forces at Adowa and waited. Both sides were waiting for the other to attack and little happened throughout February 1896 except that supplies started to run out for both sides. Menelik had set up gibbir or depots to store food for his army but even these began to empty rapidly. The Negus even began to consider retreat. The Italians' supplies would only last until March 2nd and that was on half rations. On February 29th, angered by a telegram from Crispi calling him incompetent and cowardly, and encouraged by his officers, Baratieri prepared to advance.

Baratieri planned to send his troops along different routes to meet on the high ground overlooking Adowa by dawn on March 1st. However the country was so difficult to traverse that soon the Italian forces became lost and confused. As the confusion grew great holes opened in the Italian lines and just at this time Ras Makonnen of Harar (Father of Emperor Haile Selassie I, I God and King) arrived with 30 thousand warriors to join the battle. He was joined by hordes of Menelik's warriors. In the battle that ensued wave upon wave of Ethiopian soldiers attacked the Italians, causing them to flee in total confusion. At the end of the battle 289 Italian officers, 2 918 European soldiers and about 2 000 askari (Eritreans fighting for the Italians) were dead. More were wounded, missing or captured. Menelik stopped the torture of prisoners that had caused some deaths and forced the rest of the captured troops to march to Addis Abeba where they were held until the Italian government paid 10 million lire in reparation money.

At the news of the victory at Adowa black people all over the world rejoiced. Ethiopia became a symbol of the struggle for freedom and black intellectuals and religious leaders made pilgrimages to the country. The battle of Adowa not only saved Ethiopia from colonization by Rome but raised the status of an African country to an equal partner in the world community.
When the Italians under Mussolini again invaded the country 40 years later, black people worldwide supported Haile Selassie's efforts to regain freedom for Ethiopia and celebrated on May 5th 1941 when the Emperor returned in triumph to Addis Abeba.

March 1st is a day of celebration in Ethiopia and in the RasTafari community internationally.