| Dates | Events | |
| February to September |
Allied forces occupy the Jordan Rift Valley. |
Details |
| March 21 – April 5 |
First phase of the Spring Offensive, Operation Michael (also known as Second Battle of the Somme). The Germans obtain a Pyrrhic victory. |
Details |
| March 21 – April 2 |
First Transjordan attack on Amman. |
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| March 23 – August 7 |
Artillery bombardment of Paris. |
Details |
| March 30 – April 5 |
First Battle of Villers-Bretonneux, a phase of Operation Michael. |
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| April 1 |
Royal Air Force founded by combining the Royal Flying Corps and the Royal Naval Air Service. |
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| April 4–5 |
Battle of the Avre, final phase of Operation Michael. |
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| April 7–29 |
Second phase of the Spring Offensive, Operation Georgette (also known as Battle of the Lys). The results are disappointing for the Germans. |
Details |
| April 7–9 |
Battle of Estaires, first phase of Operation Georgette. |
Details |
| April 10–11 |
Third Battle of Messines, a phase of Operation Georgette. |
Details |
| April 12–13 |
Battle of Hazebrouck, a phase of Operation Georgette. |
Details |
| April 13–15 |
Battle of Bailleul, a phase of Operation Georgette. |
Details |
| April 14 |
Ottokar Czernin resigns as Austria-Hungary's Foreign Minister over the Sixtus Affair. |
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| April 17–19 |
First Battle of Kemmelberg, a phase of Operation Georgette. |
Details |
| April 18 |
Battle of Bethune, a phase of Operation Georgette. |
Details |
| April 21 |
The Red Baron is shot down over Vaux-sur-Somme. |
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| April 23 |
Guatemala declares war on Germany. |
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| April 24–27 |
Second Battle of Villers-Bretonneux, a phase of Operation Georgette. |
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| April 25–26 |
Second Battle of Kemmelberg, a phase of Operation Georgette. |
Details |
| April 28 |
Gavrilo Princip dies in Terezín prison, from tuberculosis. |
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| April 29 |
Battle of Scherpenberg, final phase of Operation Georgette. |
Details |
| April 30 – May 4 |
Second Transjordan attack on Shunet Nimrin and Es Salt. |
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