In 1917, in a battle of WW1, the 22th and 25th regiment of the Canadian Expeditionary Forces launched an assault at night to a small village hold by the German. But the German didn't want to lose this village, so at the following morning, they sent a counter-attack. The Canadian hold their position for 4 days. Many attemps were made by the German, but without success.
One of these two division were english Canadian and the other were french Canadian. When the German heard soldier speak french, they thought the French Army sent them reinforment. So, thinking the Canadian were probably more than what they really were, they decide to gave up. What they didn't know back them, is that french is a official language in Canada, alongside with english.
Those two division, even behind the language barrier that separate them, were still togheter, fighting for the same country: Canada.