イギリスの対独宣戦布告 (1914年)

1914年8月3日、外務大臣エドワード・グレイは、庶民院でロンドンのベルギー公使館からもたらされた情報を発表した。グレイは、ベルギー当局から報せを受け、ドイツがベルギーに対して中立を保証する代わりにベルギー領内の自由通過を求め、拒否すれば敵とみなすと警告したと述べた。12時間の回答期限が設けられたが、ベルギーはドイツとの合意を交わさないつもりであるとも述べた^[1]。

1914年8月4日、イギリスの首相ハーバート・ヘンリー・アスキスは庶民院で以下のように声明を発表した^[2]。

The King of the Belgians has made an appeal to His Majesty the King for diplomatic intervention on behalf of Belgium. His Majesty's Government are also informed that the German Government has delivered to the Belgian Government a Note proposing friendly neutrality entailing free passage through Belgian territory and promising to maintain the independence and integrity of the Kingdom and its possessions, at the conclusion of peace, threatening in case of refusal to treat Belgium as an enemy. An answer was requested within twelve hours. We also understand that Belgium has categorically refused this as a flagrant violation of the law of nations. His Majesty's Government are bound to protest against this violation of a Treaty to which Germany is a party in common with themselves, and must request an assurance that the demand made upon Belgium may not be proceeded with, and that her neutrality will be respected by Germany. You should ask for an immediate reply.

8月5日、アスキス首相は、庶民院で以下のように述べた:^[3]。

Our Ambassador at Berlin received his passports at seven o'clock last evening, and since eleven o'clock last night a state of war has existed between Germany and ourselves. We have received from our Minister at Brussels the following telegram: "I have just received from Minister for Foreign Affairs—" that is the Belgian Minister for Foreign Affairs— "a note of which the following is a literal translation: 'Belgian Government regret to have to inform His Majesty's Government that this morning armed forces of Germany penetrated into Belgian territory in violation of engagements assumed by treaty.'"

同日の会議で、庶民院は戦争遂行のために、1億ポンド（2019年時点で103億ポンドに相当）の予算を決議した。

のちにウィンストン・チャーチルは以下のように記述している。

It was 11 o'clock at night – 12 by German time – when the ultimatum expired. The windows of the Admiralty were thrown wide open in the warm night air. Under the roof from which Nelson had received his orders were gathered a small group of admirals and captains and a cluster of clerks, pencil in hand, waiting. Along the Mall from the direction of the Palace the sound of an immense concourse singing "God save the King" floated in. On this deep wave there broke the chimes of Big Ben; and, as the first stroke of the hour boomed out, a rustle of movement swept across the room. The war telegram, which meant "Commence hostilities against Germany," was flashed to the ships and establishments under the White Ensign all over the world.

I walked across the Horse Guards Parade to the Cabinet room and reported to the Prime Minister and the Ministers who were assembled there that the deed was done.

—Winston Churchill^[4]

8月5日朝、植民地大臣Lewis HarcourtはCommittee of Imperial Defenceの小委員会の議長を務め、内閣に対してドイツの海外植民地の大半（ドイツ領東アフリカ、ドイツ領南西アフリカ、ドイツ領トーゴラント、ドイツ保護領カメルーン）を占領するための遠征部隊を派遣し、オーストラリアにドイツ領ニューギニアとヤップ島を占領するように求め、ニュージーランドに西サモアとナウルを占領するための部隊を派遣するように求めるべきであると勧告した^[5]。

• 西部戦線 (第一次世界大戦)#1914年 - ドイツ軍によるベルギー・フランス侵攻
• イギリスによる宣戦布告
• 第一次世界大戦下の宣戦布告
• イギリスの対独宣戦布告 (1939年)（英語版）
• アメリカ合衆国の対墺洪宣戦布告

1. ↑ “GERMANY AND BELGIUM.”. 2019年10月15日閲覧。
2. ↑ “VIOLATION OF BELGIAN NEUTRALITY.”. 2019年10月15日閲覧。
3. ↑ “Belgian Neutrality Violated by Germany.”. 2019年10月15日閲覧。
4. ↑ Churchill, Winston S. (1938). “X: The Mobiliization of the Navy”. The World Crisis 1911-1918. 1 (New ed.). London: Odhams Press Limited. p. 186 
5. ↑ Douglas Newton, The Darkest Days: the truth behind Britain's rush to war, 1914 (London and New York: Verso, 2014, ISBN 9781781683507), pp. 279, 364