劳师动众 mobilize a large number of people
Explanation
劳师动众，指的是费力地调动很多人和资源去做某件事。现在常用来形容办事小题大做，花费人力物力过大。
The idiom describes expending significant effort and resources to accomplish something. It is commonly used to describe doing something unnecessarily elaborately or with excessive manpower and resources.
Origin Story
话说三国时期，蜀汉丞相诸葛亮率领大军北伐曹魏，意图一举收复中原。但他年事已高，身体抱恙，几次北伐都未能取得决定性胜利，反而损兵折将。一次，诸葛亮在军营中召集众将商议军务，军师马谡进言道："丞相，如今我军兵强马壮，士气高昂，不如趁此良机，大举进攻曹魏，一举收复失地！"诸葛亮听罢，沉吟片刻，说道："马谡，你说的虽好，但北伐并非儿戏，需谨慎行事。此次北伐，我已精打细算，调兵遣将，然劳师动众并非长久之计，若操之过急，恐损耗过大，得不偿失。兵贵神速，但更贵在精兵强将，而非一味求多。"
During the Three Kingdoms period in China, Zhuge Liang, the chancellor of Shu Han, led numerous campaigns against Cao Wei, hoping to reclaim central China. However, as he aged and several campaigns ended unsuccessfully with heavy losses, he decided on a different strategy. At a military conference, Ma Su suggested launching a full-scale attack on Cao Wei. Zhuge Liang wisely responded: "While it is good to seize the opportunity, northern campaigns are not child's play. We must proceed with caution. Mobilizing such a large army is not a sustainable long-term plan; acting too hastily may lead to excessive losses, defeating the purpose. While speed is important in warfare, having a strong and elite army is paramount, rather than merely a large one."
Usage
常用于形容办事小题大做，花费人力物力过大，也指调动很多人去做某件事。
Often used to describe doing something unnecessarily elaborately or with excessive manpower and resources; it also refers to mobilizing many people to do something.
Examples
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为了这么一件小事，就劳师动众，真是小题大做！
wèile zhème yī jiàn xiǎoshì, jiù láo shī dòng zhòng, zhēnshi xiǎotí dàzuò
It's really making a mountain out of a molehill to mobilize such a large number of people for such a trivial matter!
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这次会议劳师动众，却没什么实际成果。
zhè cì huìyì láo shī dòng zhòng, què méiyǒu shénme shíjì chéngguǒ
This meeting involved a lot of effort, but there weren't any substantial results.