Looking on the internet deeply has found these results:

large amount is the most popular phrase on the web.

large amounts of forces 175 results on the web	large amount 140,500,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
... Tahmasp I. The Ottomans, who would receive large amounts of forces and coordinations from the vassal Crimean Khanate during several stages of the war, �... Afterwards, they immediately set up pontoon bridges and crossed large amounts of forces onto the island. The Iranians had little time to react as they were hit by�... Although Bruce had a large army, he was losing large amounts of forces at every battle he was involved in. By 1318, Bruce had only 2,000 men left. At the Battle�... Acquiring large amounts of forces in a relatively short period of time, especially voluntarily, as opposed to stable development, is a frequent phenomenon in�...	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

large amounts of forces

175 results on the web

large amount

140,500,000 results on the web

More popular!

... Tahmasp I. The Ottomans, who would receive large amounts of forces and coordinations from the vassal Crimean Khanate during several stages of the war, �...
Afterwards, they immediately set up pontoon bridges and crossed large amounts of forces onto the island. The Iranians had little time to react as they were hit by�...
Although Bruce had a large army, he was losing large amounts of forces at every battle he was involved in. By 1318, Bruce had only 2,000 men left. At the Battle�...
Acquiring large amounts of forces in a relatively short period of time, especially voluntarily, as opposed to stable development, is a frequent phenomenon in�...

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.